ANSI. Right from the ZIP archive. I do have an operational CVDU board so
if needed I could try that version/board combo.
like a software problem. The faster components are not going to fix this
one.
9mhz is plenty slow enough for what you have stuffed.
Now I have to see if I can reproduce the problem. You are using the ANSI
Post by Richard CiniAs a follow-up, I slowed the clock to 9MHz using an 18.432MHz oscillator
I had handy. There was no change in the board performance. I also checked
CONFIG.SYS and I had the EMM driver installed but not the RAM drive driver,
so I installed that. The MS-RAMDRIVE driver barfs, indicating that the EMM
driver isnât loaded. So EMM4MEM that comes with the distribution is not
loading or at least not reporting any errors.
Iâll see if I have the faster glue logic in-stock. The 32k chip I know
that I do not have.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.classiccmp.org/cini
http://www.classiccmp.org/altair32
Date: Wednesday, December 24, 2014 at 8:14 AM
Subject: Re: [N8VEM: 19134] SBC188 BIOS044 question
Thanks John. I'll drop an 8mhz osc in today and see what happens (I don't
have a 12 I don't think). I'm using the ANSI rom right from the
distribution archive.
Out of curiosity, if the board is now only operating marginally, would
the EMM4MEM driver fail to load? Mine loads fine and doesn't report any
errors.
Sent from my iPhone
Rich,
-044 represented a major re-write of the disk-dispatch codes. Memory /
startup code should be the same, With that ROM, Wyse version, I get 640K
reported okay. I presume you are using the ANSI version, or, perhaps, the
CVDU version. Why a different load should affect anything, I do not know..
AFAIK, wait state jumpers on the 4MEM have never had any effect, possibly
because most of the memory select lines in the 80C188 are programmed to
ignore external WAIT.
If slowing the clock from 16mhz to 12/14mhz fixes the problem, then
slower components may be to blame. I would install faster components
(LS->ALS, or F) in the following locations: 32Kmem, U10 (LS30), U24
(LS14). If a slower clock on the CPU board changes nothing, then there may
be a BDA clobber going on in the ANSI/CVDU version of the ROM.
Don't touch the ACT138. It is a fast chip, and it MUST be CMOS for
battery backup to work.
Let me know how that clock trial works.
BTW: 4MEM may be working on the timing edge. It runs like a charm on
the Mark IV at 16mhz, but fails miserably at 16.257mhz. Anything 16.00000
or below seems to be okay.
--John
John â
Itâs a 16MHz clock and a â25 memory mapping chip. This configuration has
worked perfectly since the CPU board (v.2-007) and 4MEM were built last
year. I did swap out the two 512k chips in U0/U1 but that had no impact.
The chip select chip is an ACT138 per the schematic.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.classiccmp.org/cini
http://www.classiccmp.org/altair32
Date: Tuesday, December 23, 2014 at 8:36 PM
Subject: Re: [N8VEM: 19131] SBC188 BIOS044 question
I don't know offhand. What clock speed? 16Mhz is the fastest I've
ever been able to run the 4MEM with a 12ns memory mapping chip. 16Mhz is
its limit on the Mark IV, also. 16.257Mhz will not work on Mark IV.
--John
John â
I just âupgradedâ to the 044 version of the ROM (from 043) and noticed
that now the system memory count in the POST shows 544k (or sometimes 576k)
rather than 640k. Thatâs a difference of 64k or 96k, depending.
Any ideas why this might be? The 4MEM board was untouched.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.classiccmp.org/cini
http://www.classiccmp.org/altair32
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