Ray BarnholtThis #ModemMonday is dedicated to a great modem user. you know who we're talking about
Ccollet
CefiarNo #ModemMonday post today. Heads up that they might be a bit spotty over October.
Why? I'm currently restoring an Applix1616 kit computer for #RetroChallenge 2023. You can see full details of what I was up to today (and previously) over on the ACMS Forum: https://forum.acms.org.au/t/retrochallenge-2023-10-applix1616-restoration-documentation/503/4
RetroChallenge 2023/10 - Applix1616 restoration/documentation
So haven’t done a huge amount due to unforeseen personal circumstances that I won’t really go into here, except to say that it’s made a bit of an emotional impact over the last few days that has left me drained. Managed to get my hands on an old Taxan SuperVision IV CRT monitor. It didn’t come with a cable (which I was hoping for), so I had to make one. The Taxan screen takes RGB video in on a DIN 8 pin socket on the back, so needed to wire up a DE9 connector to a DIN 8 pin plug suitable for t...
Some more on the Telxon 1200 AA:
Here's the inside of the Telxon 1200 AA. You can see where on a Sendata 2000 the front switches would be located. Instead, there's a few pins jumpered, a few bodge wires run across the board, some extra resistors in places and even a small IC, an LM358 op amp, soldered on top of the existing components.
This modem is pre-AT command set. All the auto-answer circuitry and call end detection was done using basic electronics, with the CD line being used to tell the computer a connection had been made.
FWIW: Telxon made portable, battery powered, barcoding equipment. These were used by sales reps and chain store staff such as supermarkets and hardware stores to place product orders. This modem usually sat in an office in Auto-Answer mode. The person ordering would call the number and send in an order from their device, holding the device up to the phone handset, using it as an acoustic modem.
Time once again for #ModemMonday
This one is a Telxon 1200 AA, which is actually a specialised version of a Sendata 2000 without the large front buttons. This reduced the cost of the device, which would have been pushed for by Telxon.
This device would have been made about 1986 based on the date codes on certain internal parts.
Once again, it's time for #ModemMonday
Today's modem is a Dataplex Access 34. However, on the inside, the PCB in this modem was actually made by APT Pty Ltd, who traded as InterLink Electronics.
Particularly as speeds progressed to 28.8kbps and beyond, this rebranding/reboxing became a much more common practice within Australia.
Not only 2 modems, but 2 modem posts! Here's the inside of the Microcom Deskporte FAST modems from the last post.
Inside of the plastic case is coated in a brown conductive paint. The modem chipset is a Rockwell 288DPi, using what appears to be a Zilog Z80 to manage everything. The main difference between them seems to be where the components have been sourced from.
So since I missed #ModemMonday last week - Here's two modems!
This time, they're Microcom Deskporte FAST modems. One branded by Banksia (local Australian distributor for Microcom) and one only branded Microcom. I suspect the Banksia branded one is slightly newer, but not by a lot. The Banksia is marked "FAST +" while the Microcom is just marked "FAST" with a "tm" after it. I think this was simply a branding thing between these modems, though it's possible one of them has later firmware or different internals.
These modems supported MNP from level 2 right up to level 10. They even had a parallel interface, in case the serial interface wasn't up to the task of keeping up with the modem, though you'd use the serial port to do things like dialling, etc.