MB Microvision - Intel 8021 inside?

[Schnurrikowski]

Hi! I stumbled across several websites and retro magazines with hardware specs of the Microvision handheld made by Milton Bradley. I tried to verify that there was indeed an Intel CPU, namely 8021, included in earlier versions of the handheld. But I couldn't find anything that proves the Intel version. Old magazine reports from 70s/80s, service manuals or even plain pics of a circuit board showing the Intel chip - nothing came up. Was there really such a version or is this just another urban legend? Any help appreciated! Best regards, Knurri

Edited July 26, 2020 by Knurrikowski

[carlsson]

From what I know, each game has its own CPU/MCU so you wouldn't find one in the handheld system itself. Wikipedia writes that to begin with, MB used Intel 8021 and Texas Instrument TMS1100, but switched to exclusively use the TMS1100 for various reasons. Thus if you come across some of the earliest games, those might feature the Intel microcontroller.

 

The principle to have the logic on cartridge has been seen a few more times, like the Soundic SD-050/PC-50x series (using dedicated system-on-chip solutions) and Epoch Cassette Vision in Japan (not to be confused with the Epoch Super Cassette Vision). Obviously it allowed system specs to improve faster over time, but also added costs if every game would be using the same chips anyway, that need to be replicated instead of integrated once in the base system.

[Schnurrikowski]

Thanks for the info. I found some hints: Sean Riddle claimed to have 8021-dumps of three different Microvision games. Best regards, Knurri

[carlsson]

I tried to find some price lists from 1977-79 that include the 8048, 8021 etc but it was harder than expected. Other Intel, Zilog, Motorola etc chips are present in the price lists. I even found a reference for the Signetics 2650 (used in the 1292 APVS and later on Emerson Arcadia 2001) listed at $26.50 (haha) in Dec 1977, at the same time an Intel 8080A cost $16.00, an RCA CDP1802 for $19.95, a MC6800 for $24.95 and a Z80 for $29.95 (all from the same vendor). The CPU/MCU cost isn't everything but as noted if you replicate it in every game there are savings to be made by choosing the cheapest alternative that does the job.

[CatPix]

If I remember how the games are made, well the CPU is probably the biggest costly component. If I remember correctly, the 8021 is a microcontroller (a stepped-down microprocessor) with included ROm and RAM, so to make a cartridge game, it was advantageous as you didn't needed costly extra ROM and RAM, and also made PCB much simpler to design... basically just a straight connection to the console board, nothing else. So choosing cheper chip was the only way to cut cost down on the cart making, really.

[carlsson]

Yeah, it is true that it contains its ROM and RAM portion so in that case you're right that even for a system with a central CPU you would need one RAM chip in the system and a ROM chip on each game. While I did find some figures for generic PROM, EPROM and RAM chips of the day, I still don't know how much either the 8021 or the TMS1100 would cost per unit, to tell the price difference from another solution.

[CatPix]

Though, there was also how they could negociate the costs.

Nintendo managed to convince Ricoh to cut the price of their 65C02 CPU by HALF by saying they would order a crazy amount (If I recall, basically about a year worth of Ricoh's CPU production). I doubt MB did that much, but getting a 15% cut for the more expensive CPU may have been a better strategy than a 10% cut on the cheaper one.

[Schnurrikowski]

Update: The US patent No. 4,359,222 entitled "Hand-held electronic game playing device with replaceable cartridges" by Smith et. al. mentions the Intel 8021.