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The 8-Bit Era's Weird Uncle: The TI-99/4A

(bumbershootsoft.wordpress.com)
168 points rbanffy | 2 comments | 16 Feb 25 18:56 UTC | HN request time: 0s | source
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PaulHoule ◴[19 Feb 25 23:23 UTC] No.43109081[source]▶
I guess next week they're going to get to the interesting bit which is how weird the architecture actually was on that thing...

https://en.wikipedia.org/wiki/TI-99/4A

Particularly it only had 256 bytes of RAM attached to the CPU but had (I think) 16 kb of RAM attached to the video controller which the CPU could read and write through I/O registers. You could use this for non-video storage but you couldn't access it directly.

Coding in BASIC could, at the very least, hide the insanity from you.

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qiqitori ◴[20 Feb 25 00:55 UTC] No.43109829[source]▶
Speaking of interesting bits, this machine isn't actually an 8-bit computer, the CPU is 16-bit. (The video controller is 8-bit though, i.e. the VRAM data bus is 8-bits. It's also the same video controller used in various other machines, e.g. MSX.)
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jhallenworld ◴[20 Feb 25 02:54 UTC] No.43110558[source]▶
The other early 16-bit CPUs include:

National Instrument's PACE- I've never seen one used in anything: https://en.wikipedia.org/wiki/National_Semiconductor_PACE

but its bit-slice precursor, the IMP-16 was used in Aston Martin's Lagonda https://sprague.com/peter-sprague/aston-martin/

https://opposite-lock.com/topic/90934/lagonda-dashboards

General Instrument's CP1600, used in the Intellivision (a video game console yes, but there was a home computer keyboard attachment).

http://spatula-city.org/~im14u2c/chips/GICP1600.pdf

Its co-processor, the CP1640 is famous for evolving into Microchip's PIC microcontroller.

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kragen ◴[20 Feb 25 13:42 UTC] No.43114521[source]▶
Much more influential 16-bit CPUs from that era include the PDP-11's CPU, the Data General Nova's CPU, the Xerox Alto's CPU, and arguably even the 8086 and 8088. The chronology seems to go as follows:

- 01965: IBM 1130

- 01966: HP 2116A, the first model of the HP 2100 series

- 01969: Nova

- 01970: PDP-11

- 01971: IBM System/7

- 01973: Alto (not shipped. NEVER shipped)

- 01973: TI-990 (the 990/3, according to https://cozx.com/dpitts/ti990.html)

- 01974: HP 3000

- 01974: PACE (which was from National Semiconductor, not National Instruments)

- 01975: CP1600

- 01976: TMS9900 (what the TI-99/4A used)

- 01976: Tandem (first Tandem/16 shipped to Citibank)

- 01978: 8086

- 01979: 8088

- 01981: TI-99/4A

Since there were plenty of 6-bit, 8-bit, 12-bit, 32-bit, 36-bit, 60-bit, and 64-bit CPUs in the 01950s, you'd think there would be some 16-bit CPUs then too, but I can't think of any. I'd even forgotten about the HP 2100 until I went looking just now.

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1. rahen ◴[21 Feb 25 21:03 UTC] No.43132932[source]▶
I would add the Honeywell 316/516 series to the list. The 316 was the first 16-bit minicomputer, still using DTL logic. The 516 used TTL and served as the IMP 'router' in the early ARPANET. They were fairly popular before the PDP-11 took over with its brillant architecture.
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2. kragen ◴[21 Feb 25 23:31 UTC] No.43134414[source]▶
Excellent point! I provided a little more detail on the 316 and 516 in my comment yesterday, https://news.ycombinator.com/item?id=43125358.