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Bill of Materials

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Tested configurations and suggested replacements:

  • Logic:
    • Tested configurations:
      • All logic ICs, with exception of 74LS06, 74LS92, and 74LS670 are 74ALS family.
      • All logic ICs, with exception of U30 are 74LS family. U30 is 74S74.
      • Most logic ICs are 74AHCT or 74HCT. Using 74ACT for buffers and transceivers, and following TTL parts: 74LS06, 74LS92, 74LS670.
    • Suggested replacements:
      • TTL: 74ALS, 74LS, 74F families. 74F is recommended for buffers and transceivers - '573, '245 and '244 parts
      • CMOS with TTL compatible inputs: 74AHCT, 74HCT, 74ACT families 74ACT is recommended for buffers and transceivers - '573, '245 and '244 parts.
      • It is not recommended to use non-TTL compatible CMOS logic families like 74HC, 74AHC or 74AC.
      • For reliable operation on higher frequencies (more than 4.77MHz) U30 ('74 D flip-flop) must use a high speed logic, for example 74ALS74, 74F74, 74S74 or 74AHCT74.
  • CPU:
    • Tested configurations:
      • 12 MHz: NEC uPD70108HCZ-16 (NEC V20HL)
      • 10 MHz: NEC uPD70108HCZ-10 (NEC V20HL), NEC uPD70108C-10 (NEC V20), 8088-1 (AMD and Siemens)
      • 8 MHz: NEC uPD70108C-8 (NEC V20), 80C88-2 (Intel and Harris), 8088-2 (Intel, Fujitsu, Siemens)
      • 4.77 MHz: 80C88 (Harris), 8088 (Intel, NEC, Soviet clones).
      • Note: I observed some stability issue with Intel 8088 parts. This is apparently due to noise on power rails. Possible mitigation: Replacing logic with 74AHCT/74HCT series, soldering axial decoupling capacitors directly to ICs' power pins on the solder side of the PCB, using a different power supply. I did not have this issue when using Intel 8088-2 or 8088 of other manufacturers.
    • Suggested replacements:
      • Any 8088-compatible CPU in DIP40 package.
      • NEC V20HL is recommended for high performance, low power consumption, and supporting 80186+ instructions.
  • Intel 82xx series ICs  (except of U9)
    • Tested configurations:
      • Intersil 82Cxx CMOS parts. Work very stable up to 13.3 MHz, with exception of DMAC. Intersil C82C37-5 DMA has stability issues when used together with TTL logic. It works fine with 74AHCT/74HCT logic.
      • Intel, OKI and NEC 82Cxx CMOS parts. Work very stable up to 8 MHz.
      • Intel, AMD and NEC 82xx nMOS/bipolar parts. Work stable up to 8 MHz, except of AMD 8288 bus controller.
    • Suggested replacements:
      • CMOS (82Cxx) parts are recommended.
      • TTL/NMOS parts work too, but they consume much more power and get much hotter.
      • Note: AMD 8288 bus controller is not recommended (it has different timing specifications than 8288 chips of other manufacturers).
      • Note: NEC uPD8237AC-5 DMAC and NEC uPB8288D bus controller seem to be most stable at higher frequencies.
  • Keyboard controller (U9)
    • Tested components:
      • VIA VT82C42N
      • Holtek HT6542B
      • Intel P8042AHP with AMI KB-BIOS-VER-F firmware
  • RTC (U10):
    • DS12885 is the recommended part.
    • DS12C887A or DS12887A RTCs. In this case X2 crystal and BT1 battery holder are not required. The downside of it - when the battery inside the RTC module dies, the entire RTC module must be replaced.
    • DS12C887 and DS12887 are not recommended, since they don't support RAM clear function.
  • Flash memory:
    • 29F010/29C010 ICs should be used.
    • The board provides 17-bit address to the flash memory, so it can address 128 KiB. It is possible to use larger flash memory chips, like 256 KiB (29F020) or 512 KiB (29F040) chips, in this case higher address pins (A17 - pin 30, and A18 - pin 1) should be connected to the ground.
  • Minimal system configuration (might require BIOS tweaks):
    • Only one SRAM chip (U11). This limits system memory to 512 KiB. U27 and U35 are not required in this case, and two positions DIP switch could be used (connected to pins 7-10).
    • Only one PIC (U5). In this case IR2 (pin 20) of U5 should be connected to IRQ9 input on ISA bus (or pin 19 of U6). This limits number of system interrupts to 8, and it won't be possible to use PS/2 mouse, RTC wake-up interrupt and NPU error reporting using interrupt 13h.
    • No RTC (U10). This will definitely require BIOS modifications.
    • No PS/2 mouse support. P2, C49 and C50 are not required in this case. J3-J5
    • 8087 math coprocessor is completely optional. In fact very few IBM PC or IBM PC/XT machines had a coprocessor, so not many programs rely on it.
    • On-board LEDs (D1, D2) and reset switch (SW1) are optional.
  • Remarks for the Bill of Materials list
    • Suppliers and part numbers recommendations are based on my own findings, and they are certainly not complete, and even may contain some errors. There are many more electronic components suppliers, and it is possible that you'll find better deals elsewhere.
    • Question mark (?) after part number means that component should be compatible according to its description, but I never ordered one, and so I was not able to confirm its compatibility. Please double check before ordering.
    • Asterisk (*) after quantity means that component is optional in certain conditions. Please read notes for more information.
Showing 68 items
Part TypePart NumberDescriptionSocket TypeReferencesQuantitySupplier/Part#Notes
Part TypePart NumberDescriptionSocket TypeReferencesQuantitySupplier/Part#Notes
Capacitor 10uF, 16V Electrolytic Radial Capacitor None C43, C46 Jameco - 330692?  
Capacitor 9-50pF Ceramic Trimmer Capacitor 5mm None C52 1* Mouser - 81-TZ03R300F169B00; Jameco - 136979 Optional to tune system frequency for original CGA adapters. If not used replace with a wire bridge. 
Capacitor 47pF Disc Radial Ceramic Capacitor None C47 - C50 Mouser - 80-CK05BX470K-TR; Jameco - 1947036?  
Capacitor 33pF Disc Radial Ceramic Capacitor None C44, C45 2* Mouser - 80-CK05BX330K-TR; Jameco - 1947010? Required only when using CMOS version of U1 - 82C84. For 8284 install R7 and R8 instead 
Capacitor 0.1uF Monolithic Radial Ceramic Capacitor None C1 - C42 42 Mouser - 80-C323C104K5R; Jameco - 25523  
Capacitor 0.01uF Monolytic Radial Ceramic Capacitor None C51 Mouser - 80-C322C103K1R5CA; Jameco - 597281?  
Connector 1x2 pin Header, 1 row, 2 pin, Straight, 2.54mm None J15 Jameco - 2076957  
Connector Mini-DIN 6 pin Mini-DIN,6 pin, Female, Right Angle None P1, P2 2* Mouser - 806-KMDGX-6S-BS2715C (purple), 806-KMDGX-6S-BS3395C (green); Jameco - 119475, 961303? Only one is required if not using PS/2 mouse. Mouser offers color-coded connectors (purple - keyboard, green - mouse) 
Connector 1x3 pin Header, 1 row, 3 pin, Straight, 2.54mm None J3 - J5 3* Mouser - 649-69190-103HLF, Jameco - 2077087? Optional - could be replaces with wire jumpers (pins 1-2 for PS/2 mouse mode, pins 2-3 for AT keyboard only / no mouse mode) 
Connector 1x13 pin; 1x10 pin Header, 1 row, 13 pin, Straight, 2.54mm; Header, 1 row, 10 pin, Straight, 2.54mm None J1, J2 ,P3 - P5 Mouser - 649-68000-113HLF, 649-69190-110HLF 10 pin should be used if not using turbo mode, or using software controlled turbo mode only (in this case solder a jumper between pins 2-3 of J2) 
Connector CR2032 Battery Holder Battery Holder For CR2032, PCB Mount None BT1 1* Mouser - 122-2620-GR; Jameco - 355434; RadioShack - 270-009 Required only when using DS12885 RTC (U10). 
Connector 2x9 pin Header, 2 rows, 18pin, Straight, 2.54mm None J6 - J14 1* Jameco - 2076877? Optional - if LA17-LA23 signals are required on ISA bus. Could be replaced by wire junipers if you're certain that LA* signals are required in your system. 
Crystal 32768Hz Crystal, Tuning Fork None X2 1* Mouser - 732-C001R32.76K-APB; Jameco - 14584?, 325244? Required only when using DS12885 or DS12885A RTC (U10). 
Crystal 14.31818MHz Crystal, HC-49/UA None X1 Mouser - 73-XT49S1431-20; Jameco - 537799?; Unicorn  
Diode 1N4148 Diode, Switching None D1 Jameco - 36038?,179215?,743285?  
Diode SSF-LXH240GYD; LTL-42D1NMHDP1 LED Bi-Level Uni-Color Green/Yellow 565nm/585nm 2-Pin None D2, D3 Mouser - 696-SSF-LXH240GYD; Jameco - 2006676?  
Fuse 1.1A Fuse, Resetable, Radial None F1 1* Mouser - 576-16R110BPR; Jameco - 199912?,866955? Optional - required for short cut protection on PS/2 devices. (Normally these devices won't short cut, and even if they ever will power supply might provide adequate protection) 
Integrated Circuit 74ALS139 Dual 1-of-4 Decoder / Demultiplexer DIP16-300 U26, U27 Unicorn  
Integrated Circuit 8237 Direct Memory Access Controller DIP40-600 U7 Unicorn 82C37 is not recommended. 
Integrated Circuit 74ALS175 Quad D Flip-Flop DIP16-300 U24, U25 Unicorn Replacements: 74F175. 
Integrated Circuit 74LS06 Hex Inverter Buffer/Drivers with Open Collector High Voltage Outputs DIP14-300 U36 Unicorn; Jameco - 46359? Replacement: 7406 
Integrated Circuit 74F245 Octal Bidirectional Transceiver with 3-State Outputs DIP20-300 U18 - U21 Jameco - 287144 Replacements: 74ALS245, 74LS245. 
Integrated Circuit 74ALS20 Dual 4-Input NAND Gate DIP14-300 U34 Unicorn  
Integrated Circuit 82C54 or 8254 Programmable Interval Timer DIP24-600 U8 Jameco - 52716?, 52708?; Unicorn  
Integrated Circuit 82C59A or 8259A Programmable Interrupt Controller DIP28-600 U5, U6 Jameco - 52783?; Unicorn  
Integrated Circuit DS12C887, DS12887A, DS12885 Real Time Clock and NVRAM DIP24-600 U10 Jameco - 2059356? (DS12887A), 1194513? (DS12885) DS12885 requires the X1 crystal and a battery. 
Integrated Circuit AS6C4008 Asynchronous SRAM, 512Kbit x 8, 55ns DIP32-600 U11, U12 2* Jameco - 1927617 At least one SRAM chip is required (in this case system memory will be limited to 512 KiB). 
Integrated Circuit 82C84A or 8284A Clock Generator and Driver For 8066, 8088 Processors DIP18-300 U1 Unicorn; Jameco - 52871?  
Integrated Circuit 8088 or V20 Microprocessor DIP40-600 U2 Jameco - 52142? (8088), 52169? (8088-2), 34358? (V20); Unicorn Any 8088 compatible CPU (8088, 80C88, V20, V20HL). 8 MHz or higher (e.g. 8088-2, 8088-1, or V20 8 MHz) is required for Turbo mode operation. V20 is the recommended CPU. 
Integrated Circuit VT82C42 or Intel 8242 compatible Keyboard Controller DIP40-600 U9 Other 8042 or 8242 controller with keyboard firmware, or compatible keyboard controller, for example VT82C42. Can be pulled from 286-Pentium motherboards. 
Integrated Circuit 74ALS11 Triple 3-Input AND Gate DIP14-300 U35 Unicorn  
Integrated Circuit 74LS92 Divide-by-Twelve Counter DIP14-300 U29 Unicorn  
Integrated Circuit 8087 Math Coprocessor DIP40-600 U3 1* Other Optional. Coprocessor frequency should match or exceed CPU frequency. 
Integrated Circuit 74F244 Octal Buffer/Line Driver with 3-State Outputs DIP20-300 U22, U23 Unicorn Replacements: 74ALS244, 74LS244. 
Integrated Circuit 82C88 or 8288 Bus Controller DIP20-300 U4 Unicorn Use 82C88 or NEC uPB8288D for best results. AMD 8288 is not recommended. 
Integrated Circuit 74LS670 4 x 4 Register File with 3-State Outputs DIP16-300 U14 Unicorn  
Integrated Circuit 74ALS32 Quad 2-Input OR Gate DIP14-300 U32, U33 Jameco - 44134  
Integrated Circuit 74ALS04 Hex Inverters DIP14-300 U37, U38 Jameco - 245307  
Integrated Circuit 74ALS00 Quad 2-Input NAND Gate DIP14-300 U40, U41 Jameco - 245294  
Integrated Circuit 74ALS02 Quad 2-Input NOR Gate DIP14-300 U39 Unicorn  
Integrated Circuit 74F573 Octal D-Type Latch with 3-State Outputs DIP20-300 U15 - U17 Jameco - 282642 Replacements: 74ALS573, 74LS573. 
Integrated Circuit 74ALS138 1-of-8 Decoder/Demultiplexer DIP16-300 U28 Jameco - 309614  
Integrated Circuit 29F010 or 29C010 NOR Flash, 128Kbit x 8, 70ns DIP32-600 U13 Jameco - 242608 (70ns), 242595? (90ns), 242587? (120ns) Can be pulled from a Penitum+ motherboard. Must be preprogrammed with BIOS. 
Integrated Circuit 74ALS74 Dual D-type Flip-Flop with Set and Reset DIP14-300 U30, U31 Unicorn  
Oscillator 24MHz Oscillator, Full Can, TTL DIP14-300-OSC U42 1* Unicorn Required for turbo mode only. 24MHz for 8MHz CPU, 30MHz for 10MHz CPU, 36MHz for 12MHz CPU 
Other Keystone 9205 ISA Bracket, Keystone 9205 with holes for connectors, LEDs, and reset switch None  Mouser - 534-9205  
Other PCB Version 1.0 Sergey'XT PCB Version 1.0 None  Sergey  
Resistor 1k Resistor, Carbon Film, 0.25W None R5 Jameco - 690865?  
Resistor 10k Resistor, Carbon Film, 0.25W None R2 Jameco - 691104  
Resistor 33 Ω Resistor, Carbon Film, 0.25W None R6 Jameco - 690507?  
Resistor 100k Resistor, Carbon Film, 0.25W None R1 Jameco - 691340?  
Resistor 150 Ω Resistor, Carbon Film, 0.25W None R3, R4 Jameco - 690662?  
Resistor 510 Ω Resistor, Carbon Film, 0.25W None R7, R8 2* Jameco - 690793? Required only when using bipolar version of U1 - 8284. For CMOS 82C84 install C44 and C45 instead. 
Resistor Array 470 Ω x 5 Resistor Network, SIP 6PIN None RR4 Mouser - 264-470-RC; Jameco - 771770?  
Resistor Array 10k x 9 Resistor Network, SIP, 10PIN None RR1, RR3 Mouser - 266-10K-RC; Jameco - 24643  
Resistor Array 10k x 5 Resistor Network, SIP, 6PIN None RR2, RR5 Mouser - 264-10K-RC; Jameco - 268032?  
Socket DIP20-300 Socket, 20 pos, 300 mil width None U4, U15 - U23 10 Jameco - 112248  
Socket DIP18-300 Socket, 18 pos, 300 mil width None U1 Jameco - 112231  
Socket DIP32-600 Socket, 32 pos, 600 mil width None U11 - U13 Jameco - 112301  
Socket DIP14-300 Socket, 14 pos, 300 mil width None U29 - U41 13 Jameco - 112214  
Socket DIP24-600 Socket, 24 pos, 600 mil width None U8, U10 Jameco - 112266  
Socket DIP14-300-OSC Socket, 14 pos, 300 mil width, 4 pin, Oscillator None U42 1* Jameco - 133006 Required only if U42 will be installed. Regular 14 pin DIP socket could be used instead. 
Socket DIP16-300 Socket, 16 pos, 300 mil width None U14, U24 - U28 Jameco - 112222  
Socket DIP28-600 Socket, 28 pos, 600 mil width None U5, U6 Jameco - 112272?  
Socket DIP40-600 Socket, 40 pos, 600 mil width None U2, U3, U7, U9 Jameco - 112311  
Switch 8 POS DIP 8 positions,DIP None SW2 Unicorn, Jameco - 38842?  
Switch PTS645VL39LFS; Omron B3F-3122R Switch, Tactile, SPST, Right Angle None SW1 Mouser - 611-PTS645VL39LFS; Jameco - 1953575?  
Transistor PN2222A NPN General Purpose Amplifier None Q1 Jameco - 178511?, 178512?; Unicorn  
Showing 68 items