Multitech MicroProfessor MPF-1 Plus: Part 2 (Starting the video interface build)

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The boards for the updated video interface board (VIO) arrived so I've started building with what I have - awesome to have an updated version available!

https://www.electrickery.nl/comp/mpf1/VIO-MPF-IB/index.html
https://github.com/electrickery/VIO_MPF_I

The BF457 (Q1) ... is obsolete so can't be ordered from E14 or Mouser ... but seems plentiful on ebay from European sellers.

This is the BOM according to the schematic:

U1 - 7805 (5V regulator)
U2 - 74LS85 (4-bit magnitude comparator)
U3 - 74LS138 (3-to-8 decoder)
U4 - 74LS273 (octal dual flip-flop)
U5 - 74LS00 (quad 2-input NAND gate)
U6 - 74LS86 (quad 2-input XOR gate)
U7 - 74LS174 (hex flip-flop)
U8 - MC6845 (CRT controller)
U9 - 74LS151 (1-of-8 data selector)
U10 - 74LS161 (binary counter)
U11 - 2716 (2KB font ROM)
U12 - 6116 (2KB video RAM)
U13 - 74LS32 (quad 2-input OR gate)
U14 - 74LS245 (not required? see note below)
U15 - 74LS245 (octal bus transceiver)
U16 - 74LS157 (quad 1-of-2 data selector)
U17 - 74LS157 (quad 1-of-2 data selector)
U18 - 74LS157 (quad 1-of-2 data selector)
U19 - 2732 (4KB video routines)
U20 - 74LS138 (3-to-8 decoder)

Q1 - BF457 (obsolete ... ordered on ebay)
D1 - 1N4148W
X1 - 8MHz

RV1 - 220Ω
R1 - 3.3KΩ
R2 - 330Ω
R3 - 390Ω
R4 - 550Ω
R5 - 10Ω
R6 - 27Ω
R7 - 3.3KΩ
R8 - 1KΩ
R9 - 120Ω

C1 - 2.2µF
C2 - 0.1µF (100nF)
C3 - 100µF (not needed?)
C4 - 0.1µF (100nF)
C5 - 22pF
C6 - 0.1µF (100nF)
to
C17

Note from Frank's website:
"As was suspected, the bi-directional buffer U14, a 74xx245, is not required. Eight wires shorting both sides work just as well."

Other videos about the MPF-1:
https://www.youtube.com/playlist?list=PL5pwokf56wMKBFwpbaPu6he5nzCzLp9Jw



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