Friday, November 14, 2014

Article Number: 9898


by Barry Simon

Copyright (c) 1987, Capital PC User Group Inc.

This material may be republished only for internal use

by other not-for-profit user groups.

Posted on Compuserve with permission of CPCUG. May not be

reproduced without including the above copyright notice.

Published in the March 1987 issue of the Capital PC Monitor;

discussion of extended memory has been changed from the published


I/O, I/O, Its Off to Work We Go!

There is much noise made about running 286 based machines at 8, 10

or even 12 Megahertz. While running your computer's

microprocessor at a faster speed will make a difference, for many

tasks the difference is bounded because the limiting factor is

often the speed of your input and output devices known

collectively as I/O. That these devices slow down the CPU is seen

by the typical times involved. 8 MHz means that the CPU goes

through 8 million cycles per second. Since a single instruction

on the 80xx family of chips takes from two to over twenty cycles,

a CPU in the current generation of MS-DOS machine can run at

roughly 1 MIPS (millions of instructions per second).

Memory chips are rated at speeds of 70-200 nanoseconds. A

nanosecond is a billionth of a second which means that such chips

are capable of speed comparable to CPU speeds. That the speeds

are slightly less is shown by the need for "wait states", which

slow down the CPU to allow access to memory at its speed; RAM

speeds, however, are roughly equal to those of the CPU. I/O

speeds are considerably less. Even a fast hard disk rated at 20

milliseconds has a rated speed 100,000 times the speeds associated

to RAM. Of course, because the RAM speed is a statement about

each access and hard disk access times involve the first access of

a disk sector, the actual ratios are not that bad.

But memory access, even by slow memory chips, is much faster than

even speedy hard disks; diskettes are even slower. While disk

transfer rates are slower than RAM exchanges, they are speedy

compared to output through parallel or serial ports, where

transfer rates are measured in 100's of bytes per second. (1200

baud, for example, means roughly 120 characters per second.) And

your console, the name for the combined keyboard/monitor I/O

device must interface the computer's slowest component -- you;

its speeds are often the slowest of all.

There are software tools to try to speed up I/O especially by

using RAM for certain operations. This month, I'll discuss one

category of those tools -- disk caches; programs that can

substantially speed up disk access.

In this article, I discuss six commercial and one shareware disk

cache programs; the programs are:

o Emmcache, a shareware product by Frank Lozier;

o Lightning from the Personal Computer Support Group;

o Polyboost from Polytron;

o Quickcache from Microsystems Developers, Inc.;

o Speedcache from FSS Ltd;

o Super PC-Kwik from Multisoft Corp.; and

o Vcache from Golden Bow Systems.

What Is a Disk Cache?

Disk caches are based on the idea that you are likely to want to

access a file that you accessed recently. This is not only true

for obvious data files like a database which you might search

several times in a row, but also for program overlays and for the

files that DOS often consults to locate other files: the FAT and

the various directories, especially the root directory.

Thus every time that a file is accessed, a cache will keep a copy

of that file in memory set aside especially for that purpose.

Since this special memory is limited, the cache has to have an

algorithm to decide which parts of the cache to clear out to make

room for new sectors. All the caches under discussion use the

algorithm of discarding those parts of the cache which were least

recently accessed; that is, not the ones that were first read the

longest ago but rather than ones which were needed longest ago.

Whenever DOS calls for a sector from disk, the cache program

intercepts the call to check if the requested material is in the

cache memory. If it is, the copy in memory is used and a disk

access is saved. A cache can avoid anywhere from one-third to

two-thirds of your disk accesses. To allow a large cache, it is

natural to put the data part of the cache (that is, the copies of

the sectors which were read rather than code that controls this

data) in extended or expanded memory.

For safety's sake, you would not want these programs to delay

writing to disk material that DOS wants to write to disk; this is

called keeping dirty buffers and none of these programs keep dirty

buffers. However, as I'll explain, DOS does some of its own disk

caching and it does keep dirty buffers which can produce problems.

Do not confuse keeping dirty buffers, that is delaying writing to

disk, with caching writes. The latter means that the cache writes

to disk but keeps a copy of the material which is written to disk

if it is different from the copy that was read previously. For

example, if you load a file in your word processor, change it and

save it, a program that caches writes will save a copy of the

final file version in its cache while one that does not, will not

keep such a copy. All the commercial programs discussed in this

article cache writes, but Emmcache does not.

When I first started using a cache, I found the experience eerie.

I'd do some action that I often did and wondered why my disk

access light wasn't going on.

Types of Memory

In our discussion of caching, various references will be made to

the different kinds of memory that are available to microcomputer

users. These include:

o Conventional memory, the 640K of Random Access Memory (RAM)

that is readily accessible by most 8088/8086/80186 computers.

o Extended memory, the memory above 1 megabyte (up to 16

megabytes) that is accessible by 80286 computers. This memory

is not normally accessible for use as conventional memory but is

generally used for RAM disks, disk caches or print spoolers.

o Lotus/Intel/Microsoft Expanded Memory Specification (LIM EMS) and

supporting memory boards (up to 8 megabytes) are paged in and out

of conventional memory, thereby providing the user with additional

memory for supported software.

Not a Memory Cache

You should be careful to distinguish between a disk cache and

memory caches. There are circumstances where it may happen that

some of your RAM runs at a higher speed than most of your RAM. In

that case, it may pay to cache some of the reading of instructions

from the slow RAM to speed up programs with loops. Two situations

are where you add a speedup (usually 80186- or 80286-based) board

to a PC with lots of old RAM typically at 200 nanoseconds or with

386 machines where RAM that keeps up with the processor should be

rated at 100 or even 70 nanoseconds. In any event, these

situations involve a memory cache, not a disk cache which is the

subject of this article.

Caches Versus RAM Disks

You can also cut down on access to a physical disk by using a RAM

disk, that is by setting aside a part of RAM as a virtual disk

which DOS accesses as if it were an ordinary disk. There are

several differences between RAM disks and disk caches. Accessing

files from a RAM disk is often slightly faster as our time tests

will show. Moreover, the first access of a file with a cache will

be slower than later accesses. On the negative side, you must

decide in advance which files you'll want on the RAM disk; you'll

also have to be sure to copy any changed data files from the RAM

disk to a real disk or risk losing them when you power down or if

your system crashes.

Which should you use? That depends on how you use your computer.

If you only use a few programs without extensive data files, a RAM

disk is probably better if you can make one large enough to hold

what it needs to. In other circumstances, a cache may be

preferable. If you have the RAM, there may be sense in using

both: a RAM disk for your common programs and a cache to take up

the slack. Most of the cache programs have built-in procedures

to avoid caching programs from the RAM disk, allowing you to save

valuable cache space for files from your physical disks.

Read Ahead

Many caches will "read ahead", that is, read in an entire track

whenever any reading takes place. If your files are large and not

fragmented, this can give you a real speed advantage but if not,

your cache will fill up with unused material. On a hard disk

with many isolated bad sectors, read ahead can actually slow down

disk access because of phantom disk errors. Lightning, Super

PC-Kwik, and Vcache have read ahead while the others do not.

Super PC-Kwik has the advantage of having read ahead as an option

that you can turn off. The makers of Polyboost maintain that

since most hard disks have errors and fragmented files, their

lack of read ahead is a gain over the competition, but I think it

will depend very much on your individual setup. In my own case,

for example, I have turned read ahead off when running on my main

machine because of the isolated bad sectors on my hard disk.

Are Caches Dangerous?

If your word processor fouls up a file write, all you are likely

to lose is the file you wanted to save. Typically, the files in

your cache include the FATs and root directories of your disks.

If these go bad, you are likely to have real problems getting to

any of the data on your entire disk. There are various tools

which can help you recover from such a disaster, but they may not

always work. This means that caches have an inherent danger to

them. Of course, since DOS is also writing these files all the

time, you could make the argument that caches are no more

dangerous than DOS; perhaps even less so, since DOS keeps dirty


I cannot answer the questions about whether disk caches are really

dangerous. I can report that I've met several users who are sure

that problems they've had with FATs were caused by cache programs.

This may well be true, although it is also true that if you have

any problems with the logical structure of your disk and you have

a cache, you are likely to blame the cache. During the testing of

cache programs which went over six months, I lost the contents of

one of my hard disks three times. Two seemed to be hardware

problems solved in one case by a low level reformat and in the

other by a disk replacement. But the third one involved a piece

of software crashing the system; after rebooting, the root

directory on the hard disk was chopped liver. I'm suspicious that

the culprit was the cache I was using but maybe it was DOS' dirty

buffers or the program that crashed in the first place. All I can

say is that caching may be risky. You should be sure to back up

often but especially so if you have a cache. In fact, unless you

are willing to back up regularly, I recommend strongly against a

cache. On the other hand, caches are rather useful. I'm still

using a cache in spite of the problems that I had and some of

those who are certain that they had cache related problems are

still using them. And I've met people who feel that caches are

among their most important utilities.

Non-standard Setups

Because of the inherent dangers in caching and because caching

involves modifications of the disk BIOS, you need to be extremely

careful if your disk setup is non standard. You may need to

consult the vendors. Super PC-Kwik explicitly says not to use it

if you have a Bernoulli Box while Vcache says that it supports

these devices. The publishers of Vcache warned me not to use

Vcache with my 60 Meg Priam disk which I partitioned with Priam's

software into two 30 Meg drives; only large disks handled with the

VFEATURE program they they publish are compatible with Vcache. On

the other hand, Super PC-Kwik warns against disks with non-

standard sector sizes but said that it should work with software

making multiple standard DOS partitions. I was warned that they

had not tested the program with the Priam software but I can

report that it worked perfectly. Here, my advice is to check with

the publishers, be sure that you are backed up and run CHKDSK

several times a day when you first try a caching program with

anything non-standard.

With these programs, you cannot cache a network by having a cache

on your work station although you can sometimes cache the network

disks with a cache on the server. These are complex issues and

before attempting to use caches on machines connected to LANs,

you should be sure to speak with both the cache vendor and the

network vendor.

There is a second warning that needs to be made about using these

programs with AT extended memory, an option that is only available

with Polyboost, Super PC-Kwik and Vcache. Unfortunately, there

is no memory management protocol for AT extended memory provided

by the current versions of DOS. This lack of a standard means

there is potential for programs that you try to load there to not

know of each others existence and to therefore overwrite each

other. Since IBM publishes the source code for VDISK, all these

programs know about its protocol and can avoid clobbering it.

The situation is not so good for other virtual disk programs.

I've seen complaints about problems with AST's SUPERSPL program

and I've had problems with a cache in extended memory overwriting

a RAM disk set with the RAMDRV program included with Microsoft

Windows and with some versions of MS-DOS. It is unfortunate that

Microsoft has not published the specifications that this program

uses to access extended memory. So, if you are using any other

programs in extended memory and using an extended memory cache,

be sure to check out the operation of the other programs after

the cache is loaded. Super PC-Kwik and Vcache have a command

line parameter which you can use to give the program an absolute

address in extended memory at which to load and so avoid the

conflict "by hand". That they have to resort to such a kludge

speaks to the rather sorry state of extended memory support in

DOS 3.x.

A second aspect of caches in extended memory is that access of

extended memory involves features in the ROM BIOS that are not

often used in the current generation of AT software. Thus, the

operation may be improper on some AT clones. In fact, Vcache

comes with a program to test the BIOS access of extended memory.

If there is a problem, the clone maker must correct it.

Given the advent of a DOS that will access extended memory, it is

essential to get such problems rectified.

Two of the programs Speedcache and Quickcache load as device

drivers rather than as com files. Conventional wisdom would hold

that device drivers are somewhat less prone to compatibility

problems but I don't know if that is valid in these cases.

Use Your Free Cache

If you don't purchase and use one of these stand alone caching

programs, you should at least be sure to make use of the free

cache that comes with DOS. The cache size is set in units of 512

bytes called buffers. The default number, which DOS uses if you

don't specify otherwise, is two for 8088 machines and three for

80826 based machines; both are woefully inadequate. To increase

the number of buffers you must include a line


in your config.sys file. Here nn is the number of buffers that

you want and the recommended numbers tend to be from 15 to 20.

Why not take buffers=99? The algorithms that DOS uses are not as

efficient as those in commercial caches so that the time it takes

to search the buffers to see if the proper sector is in the buffer

negates the time saved once the number of buffers becomes too


What are the disadvantages of using buffers for a cache? First

there is the issue of dirty buffers. Actually, just using a

commercial cache doesn't effect this since caches still use DOS

for reading and writing and so the DOS buffers will still get

used. However, a cache that lets you decrease the number of

buffers that you use will force DOS to write its buffers to disk

more often because of space considerations. Another disadvantage

of DOS buffers is that since it is based on 512 byte chunks, if a

program requests more than that at once, DOS will always go to

disk and not check to see if the request is residing in its

buffers. Finally, there is the size issue that I mentioned; for

really large caches, you'll need a commercial program.

In short, if you don't use a commercial caching program, be sure

to put a line like


into your config.sys file.


Once loaded, cache programs act in the background and require no

action or input from the user. But some of these programs have

option switches which you'll need to study carefully to load the

program to operate in an optimal manner. For many, the defaults

will be correct, but you'all at least want to adjust the cache


What is the proper size? That's a trade off-between what else you

want to use your RAM for and how you use your machine. I have the

impression that unless your cache is at least 60K, you may be

better served by DOS buffers although for some operations, a 20K

cache will show a noticeable improvement.

Lightning has the annoying feature of using EMS memory if you have

it, even if you'd prefer to use conventional memory; it does not

support AT extended memory. As the name implies, Emmcache uses

only EMS memory. Speedcache supports the special bank switching

protocol on the Tall Tree JRAM boards as well as conventional

and EMS memory. For the other programs, you'll have to decide

whether your cache will reside in conventional, EMS or AT extended

memory and how much memory it will take. Be warned that some of

the programs default to rather unreasonable values of cache size,

such as all the remaining EMS memory or all the conventional

memory except for 232K for your remaining programs. Other

parameters vary from program to program and concern things like

what drives to cache and what algorithms to use in specific

cases. For all but the what and how much memory to use, you can

probably get away with using the defaults initially.

Super PC-Kwik has many switches and it may pay to vary some of

the switches and do some testing if some aspects of performance

seem below what you expect. For example, on the Kaypro 286i,

changing the diskette parameter from the default /d+ to /d-

resulted in an improvement of the diskettes test by a factor of

more than 4!

Memory Usage

Table 1 shows memory usage of the cache; it lists the amount of

conventional memory used by the control part of the software

exclusive of the memory taken by the cache. If you put the cache

in conventional memory, the amount in this table will be

overwhelmed by the amount of memory taken by the cache itself

but, if you place the cache in EMS or extended memory, this

figure will be quite important. For some of the conventional

memory caches, you pick only the total size of cache plus

controlling code. For these, the amount of memory in the control

part cannot be determined; these are indicated in the Table with

an *. All numbers are in kilobytes except for the first row.

For those that allow you to decrease the number of DOS buffers,

the second row can show a rather significant savings. The

figures for diskette cache give the amount needed to cache two

diskette drives; for several of the programs, diskette caching is

automatic and this amount is then listed as zero. Polyboost

suggests that you won't need to cache diskette drives if you have

a hard drive; depending on your mode of operation, that may be


All the programs except for Polyboost will cache several hard

disks from the same cache with only one loading of the control

software. Polyboost requires multiple loading of its hard disk

cache which has two unfortunate consequences: you double the

overhead involved with the cache control software and you must

dedicate memory as associated with either one hard disk or the

other; this isn't useful if you tend to work on one hard disk for

a while and then switch to the other. Polyboost's caching is

limited to two hard disks. Two of the programs, Quickcache and

Speedcache, use an "advanced" EMS call not supported in the

current version of the Xebec Amnesia board software which I was

using; therefore, I am not able to report their memory usage. In

this instance, Speedcache printed an error message and exited

without loading and Quickcache crashed the system.

(Table 1 goes here)

Time tests

Table 2 shows the results of time tests. The tests are intended

to be "real world" tests. Tests 1-4 are tests of cache read

functions. Test 1 is the time to sort a 140K database that I

had just sorted a different way. This demonstrates the savings

you would get from repeated access to a database. Test 2 is the

time to spell check a 40K document through the first pass which

checks for possible misspellings. Test 3 is the time it took to

convert a 500K database from one version of a database I had to

another. Test 4 is the time to compile, link and EXE2BIN a 100K

file which I had just treated by MASM, LINK and EXE2BIN on a hard

disk and edited. This is typical of a situation where you may

get a compiler error, correct the source file, and then


Test 5 and 6 test the ability to speed up disk writing. Test 5

is a PC Magazine "write random sectors" test. This test writes

the same data repeatedly to sectors which may be the same and so

it is particularly sensitive to the trick that caches use of

suppressing a rewrite of identical data to what was earlier

written to disk. Test 6 is a patched version of test 5 which

writes different data each time. It was supplied to me by the

publisher of Super PC-Kwik but I think it is a more significant

test than the original test 5.

The remaining tests attempt to check cache overhead or special

elements and are not as significant. Test 7 is the time it took to

copy 10 files adding to 350K from a hard disk to a floppy and

test 8 is the same for a floppy to floppy copy.

Tests 9, 10 and 11 are Norton's disk test program on a hard disk,

1.2 megabyte floppy, and regular floppy, respectively. The

Norton tests are included because the results are so dramatic.

These dramatic speed increases over DOS are due mainly to read

ahead as can be seen by running Super PC-Kwik with this option

turned off. The copy tests check on whether there is time lost

because of cache overhead.

The three columns listing DOS nn are tests done with no cache and

nn buffers. Tests 1, 2, 4, 5 and 6 were also done from a 1

megabyte RAM disk and Test 3 using two 1 megabyte RAM disks. For

vague comparison purposes only, three other times are reported

within asterisks: The time for a Norton disk test on a 2.4 Meg

RAM disk (#9), and the times to copy the same set of files used

in Tests 7 and 8 from a hard disk to a RAM disk (as #7) and from

one RAM disk to another (as #8).

All the tests are done on a Kaypro 286i with a Xebec EMS board.

To check how much overhead EMS causes, I ran the tests for Super

PC-Kwik in both EMS and conventional memory. This overhead is

due to the lack of DMA support in EMS and not to the bank

switching. Since I could not get Quickcache and Speedcache to

run under this EMS setup, I did their tests in conventional

memory which gives them a slight advantage. I used the

recommended number of DOS buffers with buffers=20 in those cases

with no recommendation about decreasing the number of buffers. I

used 256K of cache. For all the tests but Tests 8, 10 and 11,

the cache was only hard disk for those programs (Polyboost,

Vcache) with separate diskette caches. For Vcache, I used a 240K

vs. 24K split between disk and diskette caches and for Polyboost,

which requires separate caches for each diskette, I used a 256K

hard disk cache and 16K for each diskette.

(Table 2 goes here)

First, the test results illustrate the importance of increasing

buffers above the default 2 or 3 if you are not using a cache;

they also illustrate that there is a break point where too many

buffers can hurt you. On things that caches do well (Tests 1-4),

caches are competitive with RAM disks.

On Test #1 which is the most typical application of a cache, the

cache programs all showed the same rather substantial gain. While

there is a some spread on the other figures, the read tests really

don't distinguish between the different caches. On writing, I'd

give the nod to Super PC-Kwik and note that none of the tests

adequately check for caching writes. The lack of this feature in

Emmcache made me lean towards Super PC-Kwik. While Super PC-Kwik

stands out as special in a positive way on writes, it also stands

out negatively on diskette copies.

While on the subject of time tests, I should mention that

Lightning allows you to call up a screen which tells you how much

time you have saved by using the cache. Its figures are pure

fairy tale! I found that often it told me that I'd saved time in

situations where I'd actually taken more time than using

buffers=20. Presumably, it was using some algorithm giving me a

comparison on some kind of slow 8088 based machine with buffers=2.

Super PC-Kwik and Vcache will give you the more accurate listing

of the number of accesses that have been from the cache as

opposed to disk accesses.

Screen Speedup

Polyboost and Vcache come with screen speedup programs;

Polyboost also has a keyboard speedup program which I did not

test. Table 3 shows tests that I did in typing the same 111K

file to the screen that I used in my earlier articles on console

software. RAW is a program which turns on DOS' raw mode (see

February Monitor). The tests with the CRTBOST and EGABOOST

programs that come with Polyboost are done with their optional

parameters set to 1 and to 5. Setting this parameter to 6 is

equivalent to setting it to 5 and turning RAW on. Setting the

parameter to 1 is recommended for most users. Times are given in

seconds. For comparison, times are given for some of the other

screen management programs that I have considered. Fansi Console

has a "quick" parameter which can be turned on and off.

(Table 3 goes here)

While the times on EGA/CRTBOOST are impressive, it has some bugs.

When EGABOOST was installed, even with its speed parameter set to

the slowest value (1), I was unable to change monitors on a two

monitor system with either DOS' MODE command or a public domain

program that I use. There are programs that require me to use

Fansi's capability to turn Q=1 on and off from BATch files. These

programs do not work properly with CRTBOOST at its highest

settings. You can change to a setting where they do work but only

with a menu driven utility. Finally, both CRTBOOST and VSCREEN

suffer from the defect that screen speedup can be a disadvantage

if you don't also have screen scrolling memory. I have not

tested all screen scrolling memory programs with these two speedup

programs but I'd expect at least some incompatibilities. Fansi

comes with its own screen scrolling memory which even supports



Lightning comes in both copy protected and unprotected versions;

indeed, the price difference is so great that I'd call it

ransomware. Because you'll want to load the program as part of

your autoexec.bat and the copy protection is of the key disk

version, you will really need the unprotected variety. All the

other programs are not copy protected.

It seems to me that these programs, as a group, are somewhat

overpriced. They are subtle but not that complicated as can be

seen by the fact that the main programs are typically about 5K.

Indeed, in cost per byte, they may be the most expensive class of

programs on the market.

On the basis of time tests alone, it is difficult to pick one

among these programs. Your choice will have to depend on factors

like the amount of conventional memory they use, the particular

characteristics of your system as they relate to issues like read

ahead, and price.

Emmcache is a free program by Frank Lozier of Cleveland State

University. It is available to CPCUG members in a file called

EMMCACHE.ARC on the MIX BBS, (301) 480-0350.

Lightning is published by the Personal Computer Support Group,

11035 Harry Hines Blvd., #206, Dallas, TX 75229, (214) 351-0564.

The non-copy protected version is $89.95 and the copy protected

version is $49.95.

Polyboost is published by POLYTRON, 1815 Northwest 169th Place,

Suite 2110, Beaverton, OR 97006 (503) 645-1150 and lists for

$79.95. The package includes screen and keyboard speedup in

addition to the caching software.

Quickcache is published by Microsystems Developers, Inc., 214-1/2

West Main Street, St. Charles, IL 60174; it lists for $49.95.

Speedcache is published by FSS Ltd, 2275 Bascom Ave., Suite 304,

Campbell, CA 95008, (408) 371-6242 and lists for $69.95.

Super PC-Kwik is published by Multisoft Corp., 18220 SW Monte

Verdi, Beaverton, OR 97007, (503) 642-7108 and lists for $79.95.

Also available is a conventional memory cache called Personal

PC-Kwik for $39.95 and a cache without all the options and

"advanced support" called Standard PC-Kwik for $49.95.

Vcache, which includes the Vdiskette and Vscreen programs, is

published by Golden Bow Systems, P.O. Box 3039, San Diego, CA

92103, (619) 298-9349 and lists for $49.95.



Recommended buffers ³ x ³ x ³ x ³ 5 ³ 15 ³ x ³ x


Buffer memory saved ³ x ³ x ³ x ³ 7.5 ³ 2.5 ³ x ³ x


Conv. mem cache 20K ³ NA ³ 2.7 ³ * ³ * ³ 4.2 ³ 7.5 ³ 9.7


Conv. mem each add 16K ³ NA ³ 0.4 ³ * ³ * ³ 0.3 ³ 0.5 ³ 0.5


EMS memory 256K ³ 7.1 ³ 19.0 ³ 9.1 ³ 12.5 ³ 8.4 ³ * ³ *


EMS mem each add 64K ³ 1.0 ³varies³ 1.7 ³ ~0 ³ 1.1 ³ * ³ *


EMS memory 1 Meg ³19.1 ³ 36.3 ³ 30.1 ³ 12.7 ³ 21.6 ³ * ³ *


AT Ext. mem 256K ³ NA ³ NA ³ 9.7 ³ 29.4 ³ 8.9 ³ NA ³ NA


AT Ext. each add 64K ³ NA ³ NA ³ 1.7 ³ 2.0 ³ 1.1 ³ NA ³ NA


AT Ext. mem 1 Meg ³ NA ³ NA ³ 30.7 ³ 43.4 ³ 22.1 ³ NA ³ NA


Maximum cache size (EMS) ³4 Meg³ 1536K³ 2200K ³1072K ³ 15 Meg³ ? ³2000K


2 Diskette cache 16K (con) ³ 0 ³ 0 ³ 34 ³ 0 ³ 25.9 ³ 0 ³ 0


2 Diskette cache 16K (EMS) ³ 0 ³ 0 ³ 5.4 ³ 0 ³ NA ³ 0 ³ 0


Able to load twice in error³ Y ³ N ³ N ³ N ³ N ³ N ³ N


Table 1. Memory Usage of Cache Programs



#1 ³ 19 ³ 19 ³ 19 ³ 11³ 11 ³ 11 ³ 11 ³ 12³ 11³ 10³ 10³ 12


#2 ³ 43 ³ 38 ³ 39 ³ 37³ 36 ³ 38 ³ 37 ³ 35³ 32³ 35³ 34³ 33


#3 ³1550 ³ 783 ³ 814 ³615³620 ³735 ³ 650 ³ 614³ 571³1065³ 704³ 642


#4 ³ 86 ³ 80 ³ 82 ³ 75³ 75 ³ 77 ³ 75 ³ 73³ 73³ 75³ 75³ 73


#5 ³ 18 ³ 20 ³ 20 ³ 13³ 3 ³ 3 ³ 3 ³ 5³ 5³ 12³ 2³ 5


#6 ³ 18 ³ 18 ³ 20 ³ 13³ 13 ³ 12 ³ 12 ³ 5³ 5³ 12³ 11³ 5


#7 ³ 45 ³ 31 ³ 30 ³ 31³ 30 ³ 28 ³ 32 ³ 41³ 41³ 29³ 27³ *4*


#8 ³ 70 ³ 64 ³ 77 ³ 62³ 64 ³ 64 ³ 63 ³ 69³ 69³ 62³ 61³ *2*


#9 ³604 ³ 500 ³ 535 ³465³671 ³476 ³ 585 ³ 490³ 371³ 451³ 453³ *20*


#10³419 ³ 415 ³ 417 ³418³ 67 ³418 ³ 61 ³ 61³ 61³ 418³ 417³


#11³ 92 ³ 91 ³ 91 ³ 90³ 36 ³ 81 ³ 36 ³ 37³ 37³ 91³ 89³


Table 2. Time Tests on Disk Caches

EMM = Emmcache;

LIGHT = Lightning;

POLY = Polyboost;

VCAC = Vcache;

SPCK = Super PC-Kwik, all in EMS.

SCON = Super PC-Kwik;

SCAC = Speedcache;

QCAC = Quickcache, all in conventional memory.

º EGA w/o³ EGA & ³ Mono w/o³ Mono &

Program º RAW ³ RAW ³ RAW ³ RAW


ANSI º 143 ³ 120 ³ 125 ³ 93


FANSI CONSOLE/Q=0º 105 ³ 74 ³ 76 ³ 44


FANSI CONSOLE/Q=1º 32 ³ 17 ³ 38 ³ 15


FLICKER FREE º NA ³ NA ³ 34 ³ 13


NANSI º 104 ³ 66 ³ 74 ³ 38


TALL SCREEN º 204 ³ 177 ³ 174 ³ 149


VSCREEN º 90 ³ 74 ³ 61 ³ 46


POLYBOOST S=1 º 81 ³ 66 ³ 53 ³ 37


POLYBOOST S=5 º 30 ³ 13 ³ 25 ³ 10


Table 3. Time in Seconds to TYPE 111K File

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