Sinclair ZX81

Sinclair ZX81

The ZX81 was the successor to the ZX80, still based on the Zilog Z80A but with 8K ROM rather than 4K, and the same 1K RAM. The biggest technical difference was the integration of many of the ICs into one component, which reduced the chip count and the cost, starting at £49.95 for a kit, and £69.95 for a ready-built machine.

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Psion Series 3mx

Psion Series 3mx

The Psion Series 3mx was the last model in the Series 3 line, launched in mid 1998, and is an upgrad to the Series 3c. The main differences are: a silver metallic finish, a CR2025 backup battery, and a faster processor, the 16 bit NEC V30MX (80C86 compatible) running at 27.684 MHz. It has a backlight like the later models of the Series 3c.

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Psion Series 3c

Psion Series 3c portable computer

The Psion Series 3c followed on from the Psion Series 3a and predating the Series 3mx. The main differences are: a redigned case in black with a rubberised coating (that degarded into a sticky mess over time), an infrared port, and a backlight (on later models).

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Tandy WP-3 Word Processor

The Tandy WP-3 is a portable Word Processor from the lates 1980s, early 1990s, a successor to the Tandy WP-2 but with a British English dictionary. Based on the Z-80 compatible NEC 70008A-6 it had a 6 line LCD display and a very usable full-size keyboard. Powered by 6V main supply and/or 4 x AA battries with backup from a CR2340 cell.

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Psion Series 3mx SSD door microswitch repair

I recently bought a Psion Series 3mx on eBay but found it didn’t recognise SSDs inserted in either A or B slots and suspected a motherboard fault. Having found a cheap 3mx to test this, and checking that it did indeed read SSDs OK, after swapping the motherboard it didn’t help. Not only that but it also failed in the same back in the original machine.

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Sharp PC 3000

Sharp PC-3000 DOS Handheld

The PC-3000 was a DOS-based computer, the predecessor to the PC-3100, launched in 1991 following the release of the Atari Portfolio, the world’s first palmtop computer.

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Texas Instruments TI Programmable 57

Texas Instruments TI Programmable 57

The TI-57 was a programmable calculator made by Texas Instruments from 1977 to 1982, which was followed by the more powerful TI-58 and TI-59. It had 50 program steps and 8 memory registers. I owned a Texas Instruments TI-57 while at university, used very occasionally for ‘real’ problems but mainly just played with the examples…

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