2 layers350 × 224.3 mm
2 layers282.7 × 108.3 mm
Keyboard
danwerner21/TI99_2250a 2022 replica of the classic TI/994a, using obtainable parts
- Size
- 282.7 × 108.3 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 63
- Nets
- 34
- Pads
- 314
- Tracks, vias
- 390, 8
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 6 (file 20211014)
- Created
- 24 Jun 2022
- Updated
- 5 Oct 2024
Overview
Keyboard is an open-source printed circuit board by danwerner21, from the danwerner21/TI99_22 repository on GitHub. It is a 2-layer board of 282.7 × 108.3 mm with 63 parts on 34 nets, routed with 390 tracks and 8 vias.
It is built around the ATTINY13A-PU and 74LS125DC. Its parts include 48 switches, 3 resistors, 2 ICs, 2 diodes and 1 capacitor. It belongs with the keyboards and input boards and the AVR (ATmega, ATtiny) boards of this library.
Main components
2
ATTINY13A-PU
DIP-8-40℃~+85℃ 1.8V~5.5V 10bit 1KB 20MHz 6 64Byte 64Byte 8 Bit AVR Built-in FLASH DIP-8 Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)74LS125DC
-0℃~+70℃ 1 10ns@5.5V,50pF 15mA 18mA 24mA 4 4.5V~5.5V 74LS Power-off isolation、Output enable Tri-State Unidirectional - Buffers, Drivers, Receivers, TransceiversTexas InstrumentsBuffers, Drivers, Receivers, Transceivers
README
README.mdTexas Instruments TI99/4A Clone(ish) Project
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 keyboard PCB
- designing a Cherry MX keyboard
- adding headers for the GROM and expansion port to support riser cards for these ports
If there are any questions, I can be reached at vic2020Dan at gmail dot com.
ToDo
-
Cleanup/Documentation Possible Future Thoughts:
-
Redo the Board in an ATX form factor with PEB slots on board
-
Add Support for the Pico9918 on-board
-
Add Support for a Tang Nano FPGA TMS9918 replacement
-
Add Hex-bus port
-
Add a DIN 5-pin Composite video/Audio out.
-
Add built in speech synthesis
-
Clone Disk IO card
-
Relocate all the ports to the back of the motherboard
-
It has been suggested that we also have a console style version of the next revision as not everyone has a desire for a larger PE style machine
-
Also perhaps add some keys to the keyboard
DIP Switch Settings
The DIP switch on the main board allows one to configure which bank areas are populated with RAM.
RAM0 enables RAM to addresses >2000-3FFF (Lo Memory Expansion) RAM1 enables RAM to addresses >A000-BFFF (Hi Memory Expansion) RAM2 enables RAM to addresses >C000-DFFF (Hi Memory Expansion) RAM3 enables RAM to addresses >E000-FFFF (Hi Memory Expansion) RAM4 enables RAM to addresses >8000-83FF (Normal TI Scratch Pad RAM)
Note that I have never actually tested off-board 8 bit RAM, so this is new territory and might need some debugging 😊
also on-board RAM is 16 bit – so all of those external RAM sources will be slower.
Bugs
-
on rev 0.95 R36-40 are listed as 100K ohm, they are actually 100 ohm
-
on rev 0.95 the joystick and cassette connectors are mirrored and need to be mounted on the bottom side of the board to function
-
Both of these are corrected in 0.96
-
The reset button J1 should be attached to pin 5 of U1 not Pin 4
Bill of Materials
Console
| Qty | Reference(s) | Part |
|---|---|---|
| 6 | C1, C9, C11, C58, C73, C75 | 0.001uF |
| 1 | C2 | 22pF |
| 3 | C3, C5, C59 | 22uF |
| 12 | C4, C7, C13, C14, C20, C54, C55, C62, C64, C68, C71, C74 | 0.1uF |
| 1 | C6 | 1uF |
| 7 | C8, C52, C63, C65, C66, C67, C72 | 0.01uF |
| 1 | C10 | 100uF |
| 1 | C12 | 0.01uF |
| 7 | C15, C16, C17, C19, C21, C22, C60 | 100uF |
| 30 | C18, C23, C24, C25, C26, C27, C28, C29, C30, C31, C32, C33, C34, C35, C36, C37, C38, C39, C40, C41, C42, C43, C44, C45, C46, C47, C48, C49, C50, C51 | 0.1uF |
| 1 | C53 | 100uF |
| 1 | C56 | 12pF |
| 1 | C57 | 56pF |
| 1 | C61 | 220uF |
| 1 | C69 | 220pF |
| 1 | C70 | 0.022uF |
| 2 | CR1, CR4 | 1N4148 |
| 2 | CR2, CR3 | 1N914B |
| 1 | D1 | LED |
| 1 | J1 | Connector PinHeader 2.54mm:PinHeader 1x02 P2.54mm Vertical |
| 1 | J2 | Connector PinHeader 2.54mm:PinHeader 1x02 P2.54mm Vertical |
| 1 | J3 | TerminalBlock RND:TerminalBlock RND 205-00278 1x04 P5.00mm Vertical |
| 1 | J4 | Connector PinHeader 2.54mm:PinHeader 1x16 P2.54mm Vertical |
| 2 | J5, J6 | Connector PinHeader 2.54mm:PinHeader 1x03 P2.54mm Vertical |
| 1 | J7 | Connector PinHeader 2.54mm:PinHeader 1x03 P2.54mm Vertical |
| 1 | J8 | Connector PinHeader 2.54mm:PinHeader 1x02 P2.54mm Vertical |
| 1 | J9 | Connector PinHeader 2.54mm:PinHeader 1x02 P2.54mm Vertical |
| 1 | J10 | Connector Dsub:DSUB-9 Female Horizontal P2.77x2.84mm EdgePinOffset4.94mm Housed MountingHolesOffset7.48mm |
| 1 | J11 | Connector PinHeader 2.54mm:PinHeader 1x18 P2.54mm Vertical |
| 1 | J12 | Connector PinHeader 2.54mm:PinHeader 2x22 P2.54mm Vertical |
| 1 | J13 | WernerCustomLibrary:44 Pin Card Edge |
| 1 | J14 | Library:CardEdge 34Pin 2.54mm Vertical |
| 1 | J15 | Connector PinHeader 2.54mm:PinHeader 2x18 P2.54mm Vertical |
| 1 | J16 | Connector PinSocket 2.54mm:PinSocket 1x03 P2.54mm Vertical |
| 1 | J17 | Connector PinSocket 2.54mm:PinSocket 1x03 P2.54mm Vertical |
| 1 | J18 | Connector Dsub:DSUB-9 Female Horizontal P2.77x2.84mm EdgePinOffset4.94mm Housed MountingHolesOffset7.48mm |
| 1 | L1 | 0.33uH |
| 2 | L4, L5 | 6.8uH |
| 1 | L7 | 5.8uH |
| 1 | L8 | INDUCTOR (Ferrite BEAD) |
| 7 | L10, L11, L12, L13, L14, L15, L16 | 8.2uH |
| 3 | Q1, Q3, Q4 | TIS92 |
| 1 | Q2 | 2N3904 |
| 1 | R1 | 150k |
| 7 | R2, R9, R11, R18, R34, R35, R46 | 1k |
| 1 | R3 | 12k |
| 1 | R4 | 47k |
| 4 | R5, R6, R7, R8 | 22 |
| 5 | R10, R26, R45, R52, R53 | 4.7k |
| 5 | R12, R13, R14, R15, R16 | 1K |
| 3 | R17, R48, R50 | 2.2k |
| 2 | R19, R30 | 470 |
| 1 | R20 | 270 |
| 1 | R21 | 1.5k x 9 SIP bussed |
| 1 | R22 | 361 |
| 3 | R23, R73, R75 | 5.6k |
| 2 | R24, R27 | 10 |
| 1 | R25 | 150 |
| 1 | R28 | 470k |
| 1 | R29 | 0 |
| 2 | R31, R33 | 75 |
| 1 | R32 | 470 |
| 4 | R41, R42, R43, R44 | 62 |
| 1 | R47 | 3.3k |
| 9 | R36, R37, R38, R39, R40, R49, R51, R54, R56 | 100 |
| 1 | R55 | 330 |
| 1 | R57 | 10k |
| 1 | R58 | 6.8k |
| 1 | R59 | 39k |
| 1 | R60 | 6.8k |
| 4 | R61, R62, R67, R68 | 1K |
| 1 | R63 | 120k |
| 1 | R64 | 2.7k |
| 3 | R65, R66, R76 | 220 |
| 1 | R69 | 10K |
| 1 | R70 | 9.1k |
| 2 | R71, R72 | 10k |
| 1 | R74 | 5.6K |
| 1 | R77 | 15 |
| 2 | RN1, RN2 | 10K x 9 SIP Bussed |
| 1 | SW1 | DIP switchx05 |
| 1 | SW2 | Pin Header 01x02 Male |
| 1 | U1 | TMS9904 (note this needs to be a 9904 not 9904ANL. If the 9904ANL is used, Y1 needs to be substituted with 12Mhz, L1 needs to be substituted with 3.3uh and C2 needs to be substituted with 50pf) |
| 1 | U2 | TMS9900 |
| 4 | U3, U15, U22, U24 | 74LS04 |
| 2 | U4, U9 | 74LS32 |
| 2 | U5, U8 | 74LS138 |
| 1 | U6 | 74LS03 |
| 1 | U7 | 74LS08 |
| 3 | U10, U14, U18 | 74LS00 |
| 2 | U11, U41 | 74LS244 |
| 1 | U12 | 74LS373 |
| 1 | U13 | 74LS245 |
| 1 | U16 | 74LS74 |
| 1 | U17 | 74LS194 |
| 1 | U19 | LM2901 |
| 1 | U20 | LM7905 TO220 |
| 1 | U21 | LM2903 |
| 3 | U26, U27, U28 | TMC0430 |
| 3 | U29, U30, U37 | HM62256BLP |
| 2 | U31, U32 | 27C64 |
| 1 | U33 | SN76489 |
| 1 | U34 | TMS9918 |
| 3 | U35, U36, U38 | 74LS574 |
| 1 | U39 | TMS9901 |
| 1 | U40 | 74LS156 |
| 2 | U42, U43 | 74LS367 |
| 1 | U44 | 74LS379 |
| 1 | U45 | 27C010 |
| 1 | U46 | RC4558 |
| 1 | U47 | 74LS06 |
| 2 | U48, U49 | TIL119 |
| 1 | Y1 | 48.000 MHz Crystal |
| 1 | Y2 | 10.7MHz Crystal |
Keyboard
| Qty | Reference(s) | Value | Part |
|---|---|---|---|
| 1 | C1 | 0.1uF | Capacitor |
| 1 | D1 | LED | LED |
| 1 | D2 | LED | LED |
| 1 | J1 | Pin Header 1x18 male | Pin Header 1x18 male |
| 2 | R1, R2 | 470 ohm | Resistor |
| 1 | R3 | 1K ohm | Resistor |
| 48 | SW1-SW48 | Mechanical Switch | Cherry MX Switch (or compatible) |
| 1 | U1 | ATtiny13A-P | IC |
| 1 | U2 | 74LS125 | IC |
| 3 | Switch Stabilizer 2.25 | ||
| 1 | Switch Stabilizer 6.25 | ||
| 1 | Optional Alignment frame (will need modified) | ||
| Stabilizers (frame not used): | https://www.amazon.com/Genuine-Cherry-PCB-Snap-Stabilizers/dp/B085T8QZJC | ||
| Stabilizers (Frame used) | https://www.amazon.com/dp/B082X4V9VC | ||
| Frame: | https://www.amazon.com/gp/product/B07MMB33WG |
Cartridge Riser
| Qty | Reference(s) | Part | Type |
|---|---|---|---|
| 1 | J1 | Pin Header 01x18 Male | Pin Header 01x18 Male |
| 1 | J2 | 36 Pin Edge Connector | CONN EDGE DUAL FMALE 36POS 0.100 spacing |
IO Riser
| Qty | Reference(s) | Part | Type |
|---|---|---|---|
| 1 | J1 | Pin Header 2x22 Male | Pin Header 2x22 Male |
UNICORN BOARD
| Qty | Reference(s) | Part | Type |
|---|---|---|---|
| 1 | J1 | Pin Header Socket 01x16 Female Right Angle | Pin Header Socket 01x16 Female Right Angle |
| 4 | U1-U4 | Level Shifter | https://www.amazon.com/KeeYees-Channels-Converter-Bi-Directional-Shifter/dp/B07LG646VS |
| 1 | U5 | ESP32 Devkit | https://www.amazon.com/Development-Microcontroller-Integrated-Antenna-Amplifiers/dp/B09GK74F7N |
License
The original project was licensed under the Creative Commons - Attribution - ShareAlike 3.0 License
Attribution
This board was derrived from works by, uses design elements from, or contains sofware writen by the following:
- Rob Krenicki (https://github.com/rkrenicki/TI99-Motherboard)
- HackMac (https://bitbucket.org/hackmac/ti-schematics/wiki/Home)
Parts
63| Qty | Value | Footprint | References |
|---|---|---|---|
| 6 | MountingHole | MountingHole:MountingHole_3.2mm_M3_Pad | H1, H2, H3, H4, H5, H6 |
| 2 | 470Ω | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R1, R2 |
| 1 | 0 | Cherry_MX:CHERRY_PCB_100H | SW19 |
| 1 | 0.1µF | Capacitor_THT:C_Disc_D7.0mm_W2.5mm_P5.00mm | C1 |
| 1 | 1 | Cherry_MX:CHERRY_PCB_100H | SW43 |
| 1 | 1KΩ | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R3 |
| 1 | 2 | Cherry_MX:CHERRY_PCB_100H | SW44 |
| 1 | 3 | Cherry_MX:CHERRY_PCB_100H | SW45 |
| 1 | 4 | Cherry_MX:CHERRY_PCB_100H | SW46 |
| 1 | 5 | Cherry_MX:CHERRY_PCB_100H | SW47 |
| 1 | 6 | Cherry_MX:CHERRY_PCB_100H | SW23 |
| 1 | 7 | Cherry_MX:CHERRY_PCB_100H | SW22 |
| 1 | 74LS125 | Package_DIP:DIP-14_W7.62mm_Socket_LongPads | U2 |
| 1 | 8 | Cherry_MX:CHERRY_PCB_100H | SW21 |
| 1 | 9 | Cherry_MX:CHERRY_PCB_100H | SW20 |
| 1 | A | Cherry_MX:CHERRY_PCB_100H | SW30 |
| 1 | ATtiny13A-P | Package_DIP:DIP-8_W7.62mm_LongPads | U1 |
| 1 | Alpha | LED_THT:LED_D3.0mm | D1 |
| 1 | B | Cherry_MX:CHERRY_PCB_100H | SW28 |
| 1 | C | Cherry_MX:CHERRY_PCB_100H | SW26 |
| 1 | COLON | Cherry_MX:CHERRY_PCB_100H | SW7 |
| 1 | COMMA | Cherry_MX:CHERRY_PCB_100H | SW3 |
| 1 | CTRL | Button_Switch_Keyboard:SW_Cherry_MX_1.25u_PCB | SW42 |
| 1 | Computer | Connector_PinHeader_2.54mm:PinHeader_1x18_P2.54mm_Vertical | J1 |
| 1 | D | Cherry_MX:CHERRY_PCB_100H | SW32 |
| 1 | E | Cherry_MX:CHERRY_PCB_100H | SW39 |
| 1 | ENTER | Cherry_MX:CHERRY_PCB_225H | SW18 |
| 1 | EQUALS | Cherry_MX:CHERRY_PCB_100H | SW6 |
| 1 | F | Cherry_MX:CHERRY_PCB_100H | SW33 |
| 1 | FNCT | Button_Switch_Keyboard:SW_Cherry_MX_1.25u_PCB | SW48 |
| 1 | G | Cherry_MX:CHERRY_PCB_100H | SW34 |
| 1 | H | Cherry_MX:CHERRY_PCB_100H | SW11 |
| 1 | I | Cherry_MX:CHERRY_PCB_100H | SW15 |
| 1 | J | Cherry_MX:CHERRY_PCB_100H | SW10 |
| 1 | K | Cherry_MX:CHERRY_PCB_100H | SW9 |
| 1 | L | Cherry_MX:CHERRY_PCB_100H | SW8 |
| 1 | LOCK | Button_Switch_Keyboard:SW_Cherry_MX_1.75u_PCB | SW29 |
| 1 | M | Cherry_MX:CHERRY_PCB_100H | SW4 |
| 1 | N | Cherry_MX:CHERRY_PCB_100H | SW5 |
| 1 | O | Cherry_MX:CHERRY_PCB_100H | SW14 |
| 1 | P | Cherry_MX:CHERRY_PCB_100H | SW13 |
| 1 | PERIOD | Cherry_MX:CHERRY_PCB_100H | SW2 |
| 1 | Power | LED_THT:LED_D3.0mm | D2 |
| 1 | Q | Cherry_MX:CHERRY_PCB_100H | SW37 |
| 1 | R | Cherry_MX:CHERRY_PCB_100H | SW40 |
| 1 | S | Cherry_MX:CHERRY_PCB_100H | SW31 |
| 1 | SHIFT | Cherry_MX:CHERRY_PCB_275H | SW35 |
| 1 | SHIFT | Cherry_MX:CHERRY_PCB_225H | SW36 |
| 1 | SLASH | Cherry_MX:CHERRY_PCB_100H | SW1 |
| 1 | SPACE | Cherry_MX:CHERRY_PCB_625H | SW12 |
| 1 | T | Cherry_MX:CHERRY_PCB_100H | SW41 |
| 1 | U | Cherry_MX:CHERRY_PCB_100H | SW16 |
| 1 | V | Cherry_MX:CHERRY_PCB_100H | SW27 |
| 1 | W | Cherry_MX:CHERRY_PCB_100H | SW38 |
| 1 | X | Cherry_MX:CHERRY_PCB_100H | SW25 |
| 1 | Y | Cherry_MX:CHERRY_PCB_100H | SW17 |
| 1 | Z | Cherry_MX:CHERRY_PCB_100H | SW24 |
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Questions
How big is the Keyboard PCB?
It measures 282.7 × 108.3 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Keyboard use?
63 parts, built around the ATTINY13A-PU and 74LS125DC. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Keyboard KiCad files?
From the danwerner21/TI99_22 repository on GitHub, at the commit this page was made from: the board is Keyboard/Keyboard.kicad_pcb and its schematic CartRiser/CartRiser/CartRiser.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Keyboard design in my own project?
Its repository states no licence, so its author keeps all rights: ask danwerner21 before reusing the design.