PDA

View Full Version : VTech - Laser Turbo XT 8088 with EMS onboard question.



Sziklai
March 8th, 2017, 09:43 AM
Hi.
i have this board with it's manual "VTech - Laser Turbo XT - Technical Reference Manual.pdf"
On page 88 there is explanations about EMS memory.

EMM.SYS - The expanded memory manager driver program

Parameters in the device drivers:
EMM.SYS
Format: DEVICE=EMM.SYS Ma Ib [Ib...]
for M1 - C8000 - free 64k space in 384 memory (working strange: whatever i use its allocates D400 address only (but it's free anyway))
for I0 208h port as used by switch settings


The board have two banks of 41256 memories (4-5 and 6-7) 512k+512k. 9*4 chips, including parity chips.
Im using banks 4-5 only(18 chips). Address hardware switch installed as 208h and 6-7 are disabled.
placing "device=emm.sys M1 I0" line causes computer to count (and test?) 16k memory pages, mine finds 128pages = 2048kb.
After ems drivers installed MEM gives me
Total expanded (EMS) 2048k
Free expanded (EMS) 1904k

Of course it doesn't pass the ems memory test.

Has tried v4.1 v4.2 v4.3 of (C)Copyright Everex Systems emm.sys
those versions are somehow pretending to work, others emm.sys's doesn't see memory at all.
The EXP=512 key preventing emm.sys from installing - invalid parameter.
So how do i resolve this? Is it special version of emm.sys for such old board? Or maybe other ems driver?
Thank you!

modem7
March 10th, 2017, 03:57 PM
The board have two banks of 41256 memories (4-5 and 6-7) 512k+512k. 9*4 chips, including parity chips.
This is an 8-bit computer, and so a bank is 9 bits (8 data + 1 parity).
The VTech manual is referring to them as "rows".


Im using banks 4-5 only(18 chips)
So, per the manual, that is rows 5 and 6.
Page 2-5 of the manual refers to this as 'Card 1'.


Address hardware switch installed as 208h and 6-7 are disabled.
So per page 2-5 of the manual, the EMS switch bank is configured: 'card 1' set for 208h, and 'card 2' is disabled.

One 'card' is 512 KB of EMS.


... placing "device=emm.sys M1 I0" line
So, the "M1" puts the EMS frame at C8000. Note that C8000 is typically used by the ROM in XT-class hard disk controllers. I see that the manual (page 6-4) recommends M3.


Is it special version of emm.sys for such old board? Or maybe other ems driver?
At [here (http://minuszerodegrees.net/manuals.htm#VTech)], you will see a link named 'Laser Turbo XT - Software'. In that collection of Laser Turbo XT software is EMM.SYS and EMM.DOC

3pcedev
March 12th, 2017, 02:39 PM
I can confirm what modem7 says is accurate. I own a Laser Turbo XT and mine worked with the Laser version of EMM.sys

No idea if you can get it to work with a generic version of EMM.sys. I briefly tried once and had no luck.

The only variable is that my board was fully loaded (all rows) with 41256's so I ran the max amount of EMS.