Saturday, September 24, 2022

The MIPS ThinkPad, kind of

Pop quiz: what classic brand of laptop is this?

I'll give you another hint.

Bright-red TrackPoint and mouse button trim, classic keyboard font, IBM logo on the top. It's a ThinkPad ... right?

Well, obviously someone on IBM's design team wanted you to think so. But turn it on and it itself announces it's not a ThinkPad:

Say hello to the RISC ThinkPad that's not a ThinkPad, the IBM WorkPad z50.

Saturday, September 17, 2022

Refurb weekend: New batteries for the Palm Pilots

Everything portable has a battery, and every portable thing's battery dies. This is bad on earlier PalmOS devices that lack a non-volatile file system because they'll lose their data and you'll lose your mind. Fortunately many of my stable of Palm Pilots and other PalmOS devices use regular old batteries (like my original USRobotics Pilot 1000 and Handspring Visor Deluxe); of my rechargeable units, the AlphaSmart dana has a replaceable battery (I have multiple spares, or you can use regular batteries), and so does the Palm Centro, which has a non-volatile file system to boot. This is another reason why those two are my favourite Palm devices.

Thursday, September 15, 2022

Confirmed! the MOS 7600/7601 Pong chip is a true microcontroller

In a previous article I discussed the MOS 7600 and 7601 "Pong in a chip" ICs, manufactured by MOS Technology (of the famous 6502) and actually used in a number of late 1970s Pong clones, including two that eventual parent company Commodore Business Machines sold under their own name. Most notably they appeared in the Coleco Telstar Arcade console, an unusual "triangular" machine in which specific variants of the 7600 were used as its cartridges, but were also used in a number of other Pong clones through around 1978.

The question at the time was whether the 7600 actually had ROM in it (i.e., was a true microcontroller running a stored program), or whether it was simply playing games using discrete circuitry. The Telstar Arcade — and its relative, the confusingly named Telstar Gemini, not to be confused with the separate Coleco Gemini — demonstrated that other variants of the 7600 were capable of more sophisticated games than just ball-and-bat Pong variations, including primitive versions of pinball and road racing, even though most systems using the 7600 used it purely for Pong. On the other hand, no data sheets have survived to the present day and at the time my Google-fu uncovered no die photos to review, so I could find no substantiation for the occasional claims that it did.

Well, we now definitively know the answer and a bit more thanks to Sean Riddle, who actually did decap and photograph a 7600-002 die (the variant in Telstar cartridge #1, with racing, Pong and skeet shooting) and a 7600-001 (the most common three-Pong-and-skeet variant used in many machines, as well as in Telstar cartridge #2), and to Ken Shirriff, who made an extensive survey of the die, discussed with Sean and I attributes he noted, and posted a thread about it. Here's my own summary of the discussion plus a few other details I've run across since writing the original post.

Sunday, September 4, 2022

What the KIM-1 really needs is bubble memory (plus: 20mA current loop for fun and profit)

It seems like everything has flash. Flash mobs, flash photography, Flash Gordon, flash memory. (Other than the past couple years, of course, which haven't been very flash.) And, because solid-state-all-the-things, you can get flash storage devices for tons of classic computers where even the tiny microcontroller in the SD cards is probably more powerful than the systems they're being interfaced to. Why, you can even connect one to an MOS KIM-1, the famous mid-1970s MOS 6502 single-board computer. Now at last you don't need to rekey everything in or screw around with an audio recorder.

But, of course, if you've read this blog for any period of time you know I don't go in for that sort of new-fangled nonsense around here. I like my retrocomputing frivolities period-correct. What the KIM-1 really needs as a mass storage medium ... is bubble memory.