Product Overview
Intel P8039HL: the MCS-48 That Keeps Its Program Somewhere Else
Condition
New, unused New Old Stock. The photographed piece is representative of the stock on hand. It is a black 40-pin plastic DIP with the Intel logo, P8039HL, lot code L2158927, and the copyright line INTEL 77 crisply legible in white ink. The leads are bright and read as straight in these photos, with no oxidation visible; the body carries the usual molding features, a pin-1 notch at one end with two small round dimples beside it and a larger round ejector dimple set roughly 13 mm in from the opposite end. Against the millimeter rule the body measures approximately 53 mm long. Lot codes vary across stock, so the code on the piece you receive may not be the one in the photos. The sample was handled with a gloved hand for the camera.
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Product Overview
The Intel P8039HL is an 8-bit microcontroller from the MCS-48 family, built as a ROMless CPU: there is no mask ROM on the die, so every instruction is fetched from external program memory, typically an EPROM such as a 2716 or 2732 sitting alongside it on the board. It carries 128 bytes of internal RAM and 27 programmable I/O lines, runs from a nominal 5V supply, and interfaces directly with TTL logic, which is why MCS-48 designs from the era pair it so casually with plain 74-series glue. The P prefix denotes the plastic 40-pin DIP package, and the HL suffix marks Intel's HMOS version of the device; the exact maximum crystal frequency for this grade is not confirmed here, so verify it against the Intel MCS-48 datasheet before use. Within the family the 8039 is the ROMless counterpart of the 8049 and shares its 128 bytes of RAM, where the smaller 8035 pairs with the 8048 at 64 bytes. Sold each from stock on hand.
Key Features
- Manufacturer: Intel, per the logo and copyright line marked on the part
- Marking on the photographed sample: P8039HL, lot code L2158927, copyright INTEL 77
- Family: MCS-48, 8-bit architecture
- ROMless: no internal program memory, runs from external program memory
- Internal RAM: 128 bytes
- I/O: 27 programmable lines
- Supply voltage: 5V nominal
- Logic interface: directly TTL compatible
- Package: 40-pin plastic DIP, body approximately 53 mm long against the millimeter rule
- Maximum clock rating: Not confirmed - verify against the Intel MCS-48 datasheet before use
- Condition: New, unused New Old Stock. Sold each
Applications
- An arcade tech rebuilding a sound or control board whose schematic calls for an 8039 running code out of a socketed 2716 or 2732
- A retrocomputing builder bringing up an MCS-48 board where the firmware still changes between sessions and needs to live in an EPROM, not on the die
- A maintenance electrician keeping a legacy industrial controller in service when the original ROMless MCU is the one part nobody stocks anymore
- A restorer who wants a period-correct Intel HMOS device in the socket rather than a later CMOS substitute
Frequently Asked Questions
Does this microcontroller have internal program memory?
No. The 8039 is the ROMless member of the pair. It has no mask ROM at all and fetches every instruction from external program memory, which in most original designs is an EPROM on the same board.
What is the difference between the 8039 and the 8048?
The 8048 carries mask-programmed ROM on chip, so its firmware is fixed at the factory. The 8039 has none and relies entirely on external memory, which is what makes it useful where the code has to change. On RAM the 8039 matches the 8049 at 128 bytes, while the 8035 matches the 8048 at 64 bytes.
What clock speed is this part rated for?
Not confirmed. Intel published different maximum crystal frequencies across the MCS-48 grades, and we are not testing these, so check the rating for the HL grade against the Intel MCS-48 datasheet before you design around a number.
Can I substitute a CMOS 80C39 for this?
The CMOS parts are functionally similar but their drive and timing characteristics differ. In a TTL-heavy legacy design that difference can matter, which is one reason people go looking for the original HMOS device. Compare both datasheets against your board before you commit.
I need three of these, not a tube of fifty. Can I buy just three?
Yes. This is sold each, so you buy the count your build actually needs: one for the socket, one for the spares drawer, or a handful for a small production run, instead of a forced lot of fifty from somewhere else. Shipping is a flat $8, and orders over $28 ship free. Either way the order leaves our Idaho warehouse the same or next business day.
The copyright line on this one reads INTEL 77, from a stretch of years when a processor carrying no program of its own was a selling point rather than an oversight. Point it at your EPROM and it will do exactly what the board asks, one fetched byte at a time.
