John Bell Engineering was a small firm producing microprocessor many boards between 1980 and 1990.
The early boards were 6502 and Z80 SBC’s, later boards were for the Apple II, and the last ones for the IBM PC bus.
I present here, what I have found, of John Bell 6502 boards.
82-300 Three IC’s SBC 6502, 6532 2716
80-153 SBC 6522, 6502
81-260 SBC 6522, 6502
82-300
One of the smallest 6502 based computers possible with the technology of the 1980ties!
Three IC’s SBS 6502 CPU, 6532 RIOT, EPROM 2532 or 2716, expansion connector, RC oscillator, one transistor decoder.
(circuit drawn by Mike K8LH)
80-153 6502 micro
Five IC’s SBS 6502, 6522 VIA, 2716 EPROM, 2x 2114 SRAM, 74LS10 decoder
There was a revision, connecting phi2 to pin 11 of the ‘LS10, “to improve memory response”
(Clock modification with crystal, Don Sawyer)
There was a revision, connecting phi2 to pin 11 of the ‘LS10, “to improve memory response”, so the wire is soldered!
There was a revision, connecting phi2 to pin 11 of the ‘LS10, “to improve memory response”
Pages numbered are scans from this book:
See also:
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