CPU2908C
About the CPU2908C PCB
CPU2908C is an open source PCB design by m-okada, published on GitHub. It is a 2-layer board measuring 240 × 180 mm, with 585 components from 36 distinct parts.
Other key parts include the 74HC08D, TC74VHCT04AFT, TC74VHC574F, 74HC74 and TC74HC125. By type, the board carries 171 resistors, 165 diodes, 125 capacitors, 120 ICs, 3 switches and 1 connector.
From the project
Open source home brew 8-bit CPU. ---- CPU2908は、74HCシリーズ標準ロジックとROMで作る8ビットCPUです。
Open source home brew 8-bit CPU. ---- CPU2908は、74HCシリーズ標準ロジックとROMで作る8ビットCPUです。
FPGAにもインプリメントしてあります。 ターゲットデバイスはLattice MachXO2-1200HC、又は2000HCです。 FPGA版は既にプロトタイプ基版まで出来ているので、不具合を修正してリリース版を作ります。
アーキテクチャ ---- - 8ビットCPU、リトルエンディアン - 4つの汎用8ビットレジスタ。2つまとめて16ビットレジスタとして使う命令があります - 4つの16ビットアドレスレジスタ。うち1つはスタックポインタ、1つはプログラムカウンタです - 命令は全て8ビット長で、後ろにイミディエイト値が1～2バイトつく場合があります - μCode方式です - ロード／ストア命令、データ移動命令、算術／論理演算、条件ジャンプ、CALL／RET命令などがあります - CALL/JUMP命令は8/16ビットオフセット(プログラムカウンタ相対)です
Main components on the CPU2908C
CPU2908C bill of materials (BOM)
585 components, 36 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 10 | 74HC08D | SOIC-14_W3.9mm | U1, U2, U13, U21, U78, U79, U85, U89 +2 |
| 7 | TC74VHCT04AFT | TSSOP-14_4.4x5mm_Pitch0.65mm | U3, U12, U19, U26, U27, U120, U123 |
| 15 | TC74VHC574F | SOIC-20_W7.5mm | U4, U7, U9, U45, U46, U47, U48, U50 +7 |
| 4 | 74HC74 | MC74HC74ADG | U5, U6, U25, U119 |
| 1 | TC74HC125 | SN74HC11D | U8 |
| 2 | MC74HC74A | MC74HC74ADG | U10, U17 |
| 1 | 74HC86 | SOIC-14_W3.9mm | U11 |
| 1 | 74HC21 | SOIC-14_W3.9mm | U14 |
| 3 | 74HC32 | SOIC-14_W3.9mm | U15, U24, U75 |
| 27 | 74HC153 | SO-16-N | U16, U60, U61, U62, U63, U66, U67, U68 +19 |
| 9 | 74HC157 | SN74HC157DR | U18, U22, U23, U76, U77, U87, U88, U111 +1 |
| 1 | SN74HC11D | SN74HC11D | U20 |
| 12 | TC74VHCT541 | TSSOP-20_W4.4mm | U28, U30, U56, U57, U64, U65, U72, U100 +4 |
| 1 | SN74HCT574 | SN74HCT574NSR | U29 |
| 1 | NC7SZ58 | SOT-363_SC-70-6_Handsoldering | U31 |
| 4 | 74HCT273D | SOIC-20_W7.5mm | U32, U33, U34, U35 |
| 2 | AT27C1024-45JU | PLCC44 | U36, U124 |
| 3 | TC74HC161 | SOIC-16_W7.5mm | U37, U39, U41 |
| 1 | TC74HC238D | 74HC238D | U44 |
| 2 | 74HC139 | MC74HC139ADR2G | U49, U115 |
Show 16 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 3 | 74HC377 | SN74HC377NSR | U81, U82, U98 |
| 6 | CD74HC283 | CD74HC283M96 | U83, U84, U86, U93, U94, U96 |
| 1 | SN74AHC86 | SN74AHC86D | U90 |
| 1 | TC74HC4078 | SN74HC11D | U113 |
| 1 | MC74ACT125 | SOIC-14_W3.9mm | U118 |
| 1 | 74AHC1G32 | TSOP-5_1.65x3.05mm_Pitch0.95mm | U121 |
| 1 | Conn_02x20_Odd_Even | Pin_Header_Straight_2x20_Pitch2.54mm | J1 |
| 2 | LED_G | LED_0402 | S0, S1 |
| 1 | SW_DIP_x04 | SW_DIP_x4_W7.62mm_Slide | SW1 |
| 49 | LED_G | LED_0402 | D1, D2, D3, D4, D5, D6, D7, D8 +41 |
| 116 | LED_W | LED_0402 | D33, D34, D35, D36, D37, D38, D39, D40 +108 |
| 4 | 10uF | C_0603_HandSoldering | C1, C125, C126, C127 |
| 120 | 0.1uF | C_0402 | C2, C3, C4, C5, C6, C7, C8, C9 +112 |
| 1 | 47uF | CP_Radial_D8.0mm_P2.50mm | C124 |
| 167 | 47K | R_0402 | R1, R2, R3, R4, R5, R6, R7, R8 +159 |
| 4 | 10K | R_0402 | R129, R148, R149, R150 |
CPU2908C design files
The KiCad project lives in the m-okada/CPU2908 repository on GitHub; these links point at the commit this page was built from.
CPU2908C: common questions
How big is the CPU2908C PCB?
The CPU2908C measures 240 × 180 mm, has 2 copper layers and is 1.6 mm thick.
How many components are on the CPU2908C?
585 components, from 36 distinct parts. The full bill of materials is listed on this page.
Where can I download the CPU2908C design files?
From the m-okada/CPU2908 repository on GitHub, which has the KiCad layout; the links under Design files point to each one.
Can I use the CPU2908C design in my own project?
The repository has no license, so all rights stay with m-okada. Use it as a reference, and ask the author before reusing the design.
