Help on S.M. Baker's 2MB EMS/Flash 8-bit ISA card \ VOGONS

Help on S.M. Baker's 2MB EMS/Flash 8-bit ISA card

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First post, by Maxx1234

Posted on 2021-01-24, 23:24

Maxx1234 Offline

Rank Newbie

Rank: Newbie
Posts: 33
Joined: 2004-03-16, 01:58
Location: Greece

I have successfully built this card:
https://github.com/sbelectronics/emsflashboard
http://www.smbaker.com/8-bit-isa-ems-board-flash-disk-board
https://youtu.be/rj1CxmtXPWM

I have also successfully compiled the EMS driver (SBEMM) following the author's instructions (attached SBEMM.EXE).

For Bill of Materials, Component Placement and Configuration please check the attached files.

Default Configuration for EMS (Port Addres 260h, Window Address E000h, Window Size 64K)
=================================================================
SW1.1: OFF
SW1.2: OFF
SW1.3: OFF
SW1.4: ON
SW1.5: ON
SW1.6: OFF
SW1.7: OFF
SW1.8: ON
SW2.1: OFF
SW2.2: OFF
SW2.3: ON
SW2.4: ON
SW2.5: ON
SW2.6: OFF
SW2.7: OFF
SW2.8: OFF

Does anybody know (or make out from the schematics) the complete DIP switch combinations
for Bank Register Port Address and Window Address Configuration?
Also, does SW2.8 really controls the Page Frame size?

Any help would be appreciated....

Attachments

Filename

SCHEME.PNG

File size

93.81 KiB

Views

411 views

File license

CC-BY-4.0
Filename

Configuration.txt

File size

560 Bytes

Downloads

30 downloads

File license

CC-BY-4.0
Filename

Component Placement.txt

File size

673 Bytes

Downloads

34 downloads

File license

CC-BY-4.0
Filename

Bill of materials.txt

File size

1.58 KiB

Downloads

33 downloads

File license

CC-BY-4.0
Filename

SBEMM.EXE

File size

8.71 KiB

Downloads

31 downloads

File license

CC-BY-4.0

Reply 1 of 6, by Maxx1234

Posted on 2021-03-09, 13:11

Maxx1234 Offline

Rank Newbie

Rank: Newbie
Posts: 33
Joined: 2004-03-16, 01:58
Location: Greece

After some trial-and-error, I came up with the following settings:

1. Page Frame Address Configuration (SW2.1-SW2.5)
C800h ===> ON-OFF-OFF-ON-ON (Valid only when SW2.8=on)
D000h ===> OFF-ON-OFF-ON-ON
D800h ===> ON-ON-OFF-ON-ON (Valid only when SW2.8=on)
E000h ===> OFF-OFF-ON-ON-ON
E800h ===> ON-OFF-ON-ON-ON (Valid only when SW2.8=on)

2. Page Frame Window Size (SW2.8)
64K ===> OFF
32K ===> ON

The settings were verified with CheckIt Pro v1.1.

The EMS driver works fine when Page Frame Address is D000h/E000h and Page Frame Window Size is 64K.

When Page Frame Address is C800h/D800h/E800h and Page Frame Window Size is 32K and the EMS driver is loaded:
- The Page Frame Window Size is misreported as 64K
- The driver fails to load or produces errors.

Any suggestions?

Reply 2 of 6, by BloodyCactus

Posted on 2021-03-09, 15:29

BloodyCactus Offline

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Rank: Oldbie
Posts: 1426
Joined: 2016-02-03, 13:34
Location: Lexington VA

well, the ems page must must be 64kb. thats what the official EMS specifications say, so it cant be less, so the driver probably assumes that amount.

--/\-[ Stu : Bloody Cactus :: [ https://bloodycactus.com :: http://kråketær.com ]-/\--

Reply 3 of 6, by weedeewee

Posted on 2021-03-09, 16:48

weedeewee Offline

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Rank: l33t
Posts: 2912
Joined: 2021-01-31, 16:09
Location: Belgium

Cool !
Could you possibly add a battery to the card when used with sram to get a sorta flash disk ?

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

Reply 4 of 6, by Maxx1234

Posted on 2021-03-09, 17:12

Maxx1234 Offline

Rank Newbie

Rank: Newbie
Posts: 33
Joined: 2004-03-16, 01:58
Location: Greece

BloodyCactus wrote on 2021-03-09, 15:29:

well, the ems page must must be 64kb. thats what the official EMS specifications say, so it cant be less, so the driver probably assumes that amount.

AFAIK, the page frame size was laxed with the LIM EMS 4.0 specifications (unless my memory fails...).
Indeed, there is no option in the driver (which is directly derived from the lo-tech EMS driver) for a 32K window size.

Nevertheless, it would be convenient to use a reduced-size page frame window, so as to free more UMB space for
other uses (maybe someone with programming and technical knowledge would be able to look up at the available
source code and modify it...)

Reply 5 of 6, by Maxx1234

Posted on 2021-03-09, 17:14

Maxx1234 Offline

Rank Newbie

Rank: Newbie
Posts: 33
Joined: 2004-03-16, 01:58
Location: Greece

weedeewee wrote on 2021-03-09, 16:48:

Cool !
Could you possibly add a battery to the card when used with sram to get a sorta flash disk ?

This board was designed to also serve as a flash disk - just use Flash instead of SRAM chips
and set the two jumpers accordingly (more info is provided on S.M. Baker' site).

Reply 6 of 6, by weedeewee

Posted on 2021-03-09, 17:23

weedeewee Offline

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Rank: l33t
Posts: 2912
Joined: 2021-01-31, 16:09
Location: Belgium

Maxx1234 wrote on 2021-03-09, 17:14:

This board was designed to also serve as a flash disk - just use Flash instead of SRAM chips
and set the two jumpers accordingly (more info is provided on S.M. Baker' site).

Yes. I read that.
adding a well placed diode and a battery would turn it into persistent EMS memory 😀

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

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