1, 2022 at 1:50 PM wrote:
>
> --
>
> Message: 2
> Date: Wed, 20 Apr 2022 18:44:27 -0400
> From: Stephen Adolph
> To: "m...@bitchin100.com"
> Subject: Re: [M100] 5MHz and RAM in M100/T102
> Message-ID:
> <
> camcmnv6afm0q9f2uabrrumntnioumy5-3ocapocpf02vu5g...@ma
M100 upgrade instructions posted here:
https://bitchin100.com/wiki/index.php?title=5MHz_Upgrade_hacks#Instructions
comments welcome!
Steve
Interesting. I wonder what the original intent of the A* signal was then?
Jeff Birt
From: M100 On Behalf Of Stephen Adolph
Sent: Wednesday, April 20, 2022 5:44 PM
To: m...@bitchin100.com
Subject: Re: [M100] 5MHz and RAM in M100/T102
Follow up:
Great news! I had an old guy eureka
Follow up:
Great news! I had an old guy eureka moment!
So, 5MHz on T102 is pretty well baked and optimized, but an easy upgrade
for M100 was eluding me.
The main issue:
The internal stock SRAM is slowed down by the A* signal, which drives the
chip selects from signals /RD and /WR late in the machi
2x; very much noticeable. I'll have to do a video or something.
The screen io is 2x faster. It is fed through the PIO chip which is
running in step with the cpu.
In order to keep the serial port running at expected rates, the timer
portion of the PIO needs a 2.5 MHz clock though.
To keep softw
Congrats that's a really cool mod.
How does the screen scrolling seem with this mod? Faster?
-- John.
Quick update on this thread.
5MHz T102:
* working well
* stock CPU, stock main ROM, stock RAM. No change to the ICs
* changes are reduced to (1) change the oscillator (2) add a /2 clock
circuit (3) apply a modification to the RAM chip select circuit.
* serial port works as normal, printer port wo
Whoa, nice! That's great work Stephen! I'm guessing that this upgrade
process for the m100's cousins (NEC/Olivetti, etc) would also be possible,
but again with new ROM and memory (as REXCPM isn't available for the
cousins). For future consideration? :)
--Brad
On Wed, Nov 10, 2021 at 5:27 AM Steph
Thanks for the note George.
To give you a bit of info to your questions:
1) so far, I have seen no issues. Sounds are now 2x higher pitch. The
RS-232 port functionality is unchanged as it is important to feed the M100
with 2.5MHz to maintain that. I've not tested the printer port but it
should
Hi Steve,
This sounds like putting afterburners on the M100 (well, maybe more like
replacing the donkey with a mule :) and the boost in performance would be
interesting to see. I wonder:
1. Is there any impact on any of the I/Os (RS-232, Centronix port, etc.)?
2. Have you seen any appreciable i
List has been a bit quiet lately, so I thought.. why not share something
interesting that I just learned?
I have been toying quite a bit with 5MHz operation in M100 mostly but also
in T102.
In M100, I have been using 5MHz upgrades of a few different types, but they
all involve replacing the SRAM b
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