HardLabs

JFF

herraa1·JFF-TMSHAT·hardware/kicad/JFF-TMSHAT-Mainboard-Build1/jff_mainboard-1.1b-TMSHAT/jff_mainboard.kicad_pcb

JFF PCB layout, top view — open source board by herraa1

About the JFF PCB

JFF is an open source PCB design by herraa1, published on GitHub under the GPL-3.0 license. It is a 2-layer board measuring 250 × 150 mm, with 132 components from 62 distinct parts.

Other key parts include the 74LS74, Z80CPU, TL7705A, 74LS32 and 74LS574. By type, the board carries 44 resistors, 40 capacitors, 27 ICs, 12 connectors, 2 transistors and 2 crystals.

It belongs with the retro computing designs in this gallery.

From the project

JFF Computer by Skoti modified for compatibility with TMS992xA VDPs

This is an enhanced version of the JFF Computer by @Skoti, which enables the use of the TMS9928A or TMS9929A Video Display Processors (VDPs), in addition to the TMS9918A VDP.

The modified JFF mainboard 1.1b-TMSHAT Build1 has been successfully designed, built and tested (as of Aug 20th, 2025). See warning on the next paragraph.

The TMSRGBCustom TMSHAT Build1 has been successfully designed, built and tested (as of Sep 11th, 2025). It has been successfully tested for RGB output on the modified JFF mainboard 1.1b-TMSHAT Build1 with both a TMS9929A NL (50Hz) and a TMS9928AN (60Hz).

JFF, from the project README
From the project README

Main components on the JFF

74LS74Z80CPUTL7705A74LS3274LS574TMS99186225674LS0474HCT0474HC7427C25662812874LS0274LS157YM214974LS0774LS0074LS13974LS15382C55A74LS0874LS138LM311

JFF bill of materials (BOM)

132 components, 62 distinct parts.

QtyPartRefs
1
74LS74
U1
1
Z80CPU
U2
1
TL7705A
U3
2
74LS32
U4, U24
3
74LS574
U5, U8, U10
1
TMS9918
U6
1
62256
U7
1
74LS04
U9
1
74HCT04
U11
1
74HC74
U12
1
27C256
U14
1
628128
U15
1
74LS02
U16
2
74LS157
U17, U19
1
YM2149
U18
1
74LS07
U20
1
74LS00
U21
1
74LS139
U22
1
74LS153
U23
1
82C55A
U26
Show 42 more
QtyPartRefs
1
74LS08
U27
1
74LS138
U28
1
LM311
U29
1
BC548
Q1
1
BC558
Q2
1
3.579545 MHz
Y1
1
21.47727 MHz
Y2
1
SLOT1
J1
1
SLOT2
J2
1
Video
J3
1
Barrel_Jack_Switch
J4
1
DD1718PA 12V
J5
1
Joystick1
J6
1
Joystick2
J7
1
Audio
J8
1
KEYBOARD
J9
1
DIN-8
J10
1
BIOS_SW
J11
1
AV EXT
J13
1
PWR_SW
JP1
1
G5V-1-DC5
RY1
1
RESET SW
SW1
1
PWR_LED
D1
1
1N4148
D2
7
10uF
C1, C20, C21, C22, C23, C37, C39
26
100nF
C2, C3, C4, C5, C6, C7, C8, C9 +18
4
27pF
C12, C13, C14, C15
2
22nF
C38, C40
1
220uF
C41
19
10K
R1, R2, R3, R4, R5, R15, R16, R17 +11
7
470R
R6, R8, R9, R12, R13, R14, R23
1
75R
R7
2
1M
R10, R11
5
4K7
R28, R29, R35, R39, R40
1
20K
R30
1
2K2
R31
2
1K
R32, R37
1
470K
R33
2
2K7
R34, R42
1
220K
R36
1
100R
R43
1
4.7K
RN1

JFF design files

The KiCad project lives in the herraa1/JFF-TMSHAT repository on GitHub; these links point at the commit this page was built from.

JFF: common questions

How big is the JFF PCB?

The JFF measures 250 × 150 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the JFF?

132 components, from 62 distinct parts. The full bill of materials is listed on this page.

Where can I download the JFF design files?

From the herraa1/JFF-TMSHAT repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the JFF design in my own project?

Yes, under the terms of its GPL-3.0 license, which herraa1 chose for the repository.

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