19 Jun
2002
19 Jun
'02
6:50 p.m.
While you might get register-level specifications for some video chip on
an ISA or PCI card, it would be
difficult to get a production quantity of identical (obsolete) cards,
so each user would have to roll their
own. Hardly a practical approach.
Being a hardware fan, I hate to admit, it seems that the Imsai series
two is easily replaced by a CP/M emulator
program running on a PC, with the MAJOR exception being that a PC has no
front pannel.
But a software front pannel GUI could easily be developed for a modern
machine. That might make a great
learning tool for people who have not gotten to use a 'real' vintage
machine.
Tony Duell wrote:
Last I spoke
with the people at Imsai, the machine had some major issues
in my eyes...
First, its no longer a S-100 box. (deal breaker right there)... None
of your existing
S-100 stuff can be used with the machine, and with no expansion bus,
Imsai has turned
one of the first open architecture boxes into something more like a Mac
(super-Eeeek!).
Secondly, it was going to use a ISA VGA board for video display (Eeeek,
not ISA)!
I am trying to figure out how this machine is in _any_ way superior to
any of the following :
1) A CP/M machine with built-in video output (Epson QX10, etc). Not that
much CP/M software used anything other than a text terminal.
2) A random collection of S100 cards from my junk box.
3) A Z80 single-board development system connected to my PC's serial port.
All of the above would seem to do what the Imsai 2 would do -- and be
easier to maintain, easier to expand, and plain more fun to use.
This last bit was really problematic becuse the
Z800 cannot execute the
VGA bios code
in the ISA board's rom.
Can't yuo get a VGA card where the registers are documented well enough
to at least put the think into a simple text/graphics mode without using
the BIOS ROM code? In other words, ignore the ROM and hit the hardware
directly from the Z80? I know I'd have tried soemthing like that if I'd
_had_ to use a VGA card with a CP/M machine...
These issues were enough for me to realize that
the Series-2 machines
were not for me.
But the idea of having a PC motherboard in there along with the Z800
~could~ make for
a very interesting teaching platform. But once you have the PC
motherboard in there, why
run the actual Z800 CPU at all? Emulation would probably be much faster.
If the Z80/Z800 bus was availabel to the user, then the reason for
running the real hardware is obvious. But apparently it isn't.... This
seems rediculous...
-tony