Contained in the 1040ST – by Paul Lefebvre
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I’ve beforehand carried out the posts Inside the Atari 800XL and Inside the Atari 130XE and it looks like I shouldn’t be leaving the ST sequence out. This time we are going to check out the within of the Atari 1040ST.
The Atari ST was launched in 1985 and the 1040ST in early 1986. It was the primary pc to come back with 1MB of RAM for beneath $1,000. The 1040ST was the preferred mannequin of ST computer systems and bought from 1986 till it was changed with the 1040STe in 1989. I had a 1040ST (bought in 1988) and it’s the one you mostly see on eBay.
The 1040ST design was an all-in-one keyboard pc that integrated a 3.5” double-sided floppy drive into the principle unit. It additionally had a built-in energy provide which makes it fairly heavy. The following 12 months, Commodore aped the design with the Amiga 500.
Earlier than leaping inside, I’d like to notice that there appear to be fairly a couple of totally different Atari 1040ST board designs. The 2 1040STs that I’ve have barely totally different layouts. (Do any match the Byte journal image)? The 1040STe, which I don’t have, would have an much more vital structure.
Right here is the structure for considered one of my STs with board C070789-001 Rev. B:
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1MB RAM (high left). This may be beneath the facility provide.
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TOS ROM (decrease left). These are socketed chips. I’ve upgraded them to TOS 1.4, the most recent model the 1040ST can use with out further modification.
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RF modulator (lacking) high middle. My 1040ST from 1988 had an RF modulator, which was good as a result of it meant I might get by with simply the monochrome monitor and use RF with a TV for after I wished to play video games.
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The steel field in middle is the Shifter graphic chip. This tradition chip that generates the STs 3 graphics modes: 320×200 with 16 colours, 640×200 with 4 colours and 640×400 monochrome.
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Empty space on decrease proper might need been meant for the Blitter, a customized chip for transferring information round rapidly. Atari at all times claimed that they’d make the Blitter obtainable as an improve, however I don’t consider that ever occurred. Some third events produced boards that might comprise a Blitter chip, however I’m not conscious of anybody instantly including one to the board. The later 1040STe had a built-in Blitter, amongst different (minor) enhancements.
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Within the backside middle is the Motorola 68000 operating at 8Mhz, quicker than the Macintosh or Amiga on the time.
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Yamaha YM2149 sound chip (aka AY-3-8910). The was an off-the-shelf chip utilized by different computer systems and arcade machines of the time. It supplied 3-voice sounds and in addition was chargeable for serial and parallel IO.
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MMU or reminiscence administration unit (one of many chips with a clip on it) might deal with a most of 4MB of RAM regardless that the 68000 might technically deal with as much as 16MB of RAM.
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The GLU chip (generalized logic unit, one other chip with a clip on it) was a controller that supplied a approach for all the things to speak.
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Western Digital Floppy controller (WD-1772) is within the high proper and can be beneath the floppy drive. These might deal with floppies as much as 800K or so, however TOS used the usual DOS format so disks had been sometimes about 720K (double-sided). You might get extra with customized codecs, however you’d lose DOS compatibility.
The 1040ST motherboard was redesigned a number of occasions all through the years. Right here’s an alternate structure of my different 1040ST with C070523-001 Rev. D motherboard, which I consider is an older design than the one above:
On this board you’ll be able to see that the TOS ROMs are actually within the high (beneath the facility provide) and the RAM is unfold out extra alongside the underside. This explicit board additionally had a real-time clock chip hooked up through a cable to a TOS ROM socket. It was fairly a hack job and the battery was useless, so I eliminated it.
Each of those boards use the 6-chip TOS ROMs, however different (most likely newer) boards use only a 2-chip set of TOS ROMs.
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