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TI99 22

danwerner21·TI99_22·mainboard/Console.kicad_pcb

TI99 22 PCB layout, top view — open source board by danwerner21
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About the TI99 22 PCB

TI99 22 is an open source PCB design by danwerner21, published on GitHub. It is a 2-layer board measuring 350 × 224.3 mm, with 242 components from 102 distinct parts.

Other key parts include the TIM9904, TMS9900, 74LS04, 74LS32 and 74LS138. By type, the board carries 79 resistors, 75 capacitors, 47 ICs, 16 connectors, 12 inductors and 4 transistors.

It belongs with the audio designs in this gallery.

From the project

a 2022 replica of the classic TI/994a, using obtainable parts

Note that this is not a fully tested project at this point. . . .

This is based Rob Krenicki's design that is based on the HackMac KiCAD schematics. I have made several changes to the original design including:

Placing 32K of 16bit wide fast ram on the board to fully populate the address space Placing an EPROM on the main board that can be used as an on-board cartridge ROM adding a header to allow a microcontroller to replace the GROM chips (hopefully this can be moved on-board soon) replacing the video DRAM with SRAM Updating the Keyboard header to support a soft caps lock switch on the…

TI99 22, from the project README
From the project README

Main components on the TI99 22

TIM9904TMS990074LS0474LS3274LS13874LS0374LS0874LS0074LS24474LS37374LS24574LS7474LS194LM2901LM7905_TO220LM2903TMC0430HM62256BLP27C64SN76489TMS991874LS574TMS990174LS156

TI99 22 bill of materials (BOM)

242 components, 102 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
TIM9904
U1
1
TMS9900
U2
4
74LS04
U3, U15, U22, U24
2
74LS32
U4, U9
2
74LS138
U5, U8
1
74LS03
U6
1
74LS08
U7
3
74LS00
U10, U14, U18
2
74LS244
U11, U41
1
74LS373
U12
1
74LS245
U13
1
74LS74
U16
1
74LS194
U17
1
LM2901
U19
1
LM7905_TO220
U20
1
LM2903
U21
3
TMC0430
U26, U27, U28
3
HM62256BLP
U29, U30, U37
2
27C64
U31, U32
1
SN76489
U33
Show 82 more
QtyPartRefs
1
TMS9918
U34
3
74LS574
U35, U36, U38
1
TMS9901
U39
1
74LS156
U40
2
74LS367
U42, U43
1
74LS379
U44
1
27C010-C
U45
1
RC4558
U46
1
74LS06
U47
2
TIL119
U48, U49
3
TIS92
Q1, Q3, Q4
1
2N3904
Q2
1
48.000 MHz
Y1
1
10.7MHz
Y2
1
Reset
J1
1
Power LED
J2
1
POWER
J3
1
UNICORN PORT
J4
2
ROM Select
J5, J6
1
Sound Clock Select
J7
1
AUDIO OUT
J8
1
VIDEO OUT
J9
1
Keyboard
J11
1
I/O Port
J12
1
I/O Port
J13
1
GROM Port
J14
1
GROM Port
J15
1
Rom Select 1
J16
1
Rom Select 2
J17
2
1N4148
CR1, CR4
2
1N914B
CR2, CR3
1
RAM Size
SW1
1
Internal Cart ROM Enable
SW2
1
LED
D1
1
0.33µH
L1
2
6.8µH
L4, L5
1
5.8µH
L7
1
INDUCTOR (BEAD)
L8
7
8.2µh
L10, L11, L12, L13, L14, L15, L16
6
0.001µF
C1, C9, C11, C58, C73, C75
1
22pF
C2
3
22µF
C3, C5, C59
42
0.1µF
C4, C7, C13, C14, C18, C20, C23, C24 +34
1
1µF
C6
8
0.01µF
C8, C12, C52, C63, C65, C66, C67, C72
8
100µF
C10, C15, C16, C17, C19, C21, C22, C60
1
100µF
C53
1
12pF
C56
1
56pF
C57
1
220µF
C61
1
220pF
C69
1
0.022µF
C70
1
150kΩ
R1
16
1KΩ
R2, R9, R11, R12, R13, R14, R15, R16 +8
1
12kΩ
R3
1
47kΩ
R4
4
22Ω
R5, R6, R7, R8
5
4.7kΩ
R10, R26, R45, R52, R53
3
2.2kΩ
R17, R48, R50
3
470Ω
R19, R30, R32
1
270Ω
R20
1
1.5kΩ
R21
1
361Ω
R22
4
5.6KΩ
R23, R73, R74, R75
2
10Ω
R24, R27
1
150Ω
R25
1
470kΩ
R28
1
0Ω
R29
2
75Ω
R31, R33
9
100Ω
R36, R37, R38, R39, R40, R49, R51, R54 +1
4
62Ω
R41, R42, R43, R44
1
3.3kΩ
R47
1
330Ω
R55
4
10kΩ
R57, R69, R71, R72
2
6.8kΩ
R58, R60
1
39kΩ
R59
1
120kΩ
R63
1
2.7kΩ
R64
3
220Ω
R65, R66, R76
1
9.1kΩ
R70
1
15Ω
R77
2
10K
RN1, RN2

TI99 22 design files

The KiCad project lives in the danwerner21/TI99_22 repository on GitHub; these links point at the commit this page was built from.

TI99 22: common questions

How big is the TI99 22 PCB?

The TI99 22 measures 350 × 224.3 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the TI99 22?

242 components, from 102 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the TI99 22 design files?

From the danwerner21/TI99_22 repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the TI99 22 design in my own project?

The repository has no license, so all rights stay with danwerner21. Use it as a reference, and ask the author before reusing the design.

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