PRESTO vs FORTE : Choosing the Right ASIX Programmer for AVR, PIC, TI & PSoC® MCUs

Two USB in-circuit serial programmers from ASIX — same software ecosystem, same GO button, very different silicon under the hood. Here's what matters when you must pick one.

Two Tools, One Software Stack

ASIX has offered a pair of USB programmers for over a decade — PRESTO (on the market since 2004) and the higher-end FORTE (introduced in 2012). Both support hundreds of microcontrollers, serial EEPROMs, Flash chips, CPLDs, and FPGAs. Both run on the same UP software suite under Windows XP through 11 (32- and 64-bit), are bus-powered with no external supply, and get free device support updates from ASIX's website.

The divergence is in the hardware architecture: PRESTO is built around a CPLD that executes simple commands without on-board timing intelligence, while FORTE embeds a full FPGA-based processor that can carry out complex, asynchronous, and precisely timed operations entirely on the hardware side — reducing round-trip latency to the host PC.

PRESTO — Fast, cost-effective, USB Full Speed

• USB 2.0 Full Speed — 12 Mbps

• Clock output up to 3 MHz

• CPLD core — synchronous algorithms

• Voltage range: 3 V to 5 V (native); 1.2–5.5 V with adapters

• 8-pin ICSP connector, 4 data lines

• GO button + green/yellow LED status

• Overcurrent + overvoltage protection

• RoHS compliant

FORTE — Very fast, flexible, USB High Speed

• USB 2.0 High Speed — 480 Mbps

• Clock output 30 MHz / I/O cycle 15 MHz

• FPGA embedded processor — sync + async

• Voltage range: 1.8 V to 5.5 V (built-in, no adapters)

• 16-pin ICSP connector, 7 I/O lines

• GO button + green/yellow-red LED status

• Fast hardware OCP — independent of host PC

• Extended ESD (TVS diodes) · RoHS compliant

Speed & Interface

The most visible difference between the two programmers is raw throughput. FORTE's FPGA processor lets it push programming clocks at 30 MHz (output) or 15 MHz (bidirectional), compared to PRESTO's ceiling of 3 MHz. On the bus side, FORTE speaks USB 2.0 High Speed (480 Mbps) while PRESTO uses Full Speed (12 Mbps) — a 40× difference in available host bandwidth.

In practice, these combine: FORTE offloads complex sequencing onto its embedded processor so the PC round-trip is no longer a bottleneck. PRESTO can program and verify a full PIC18F8720 in 6 seconds, which is already quick for most workshop use. FORTE closes in on the theoretical maximum speed of the device being programmed.

Voltage Handling

This is where your target hardware often makes the decision for you. Modern low-power MCUs frequently run at 1.8 V or 2.5 V, and if your PCB uses one of those rails, PRESTO needs a helper board.

PRESTO NOTE

PRESTO natively operates at 5 V TTL/CMOS from USB power. Extending to 3.3 V requires the optional HPR3V3 adapter; reaching 1.2–3.6 V requires both HPR3V3 and HPR1V2. Going below 2.7 V or above 5.5 V mandates an external target supply.

FORTE ADVANTAGE

FORTE natively handles 1.8 V to 5.5 V on both supply and programming lines — no adapter hardware needed. The programming voltage "P" pin is independently variable from 6.5 V to 17 V. A calibrated on-board voltmeter (10 mV resolution) monitors VDD and P in real time, versus PRESTO's coarser 4-step detection.

PARAMETER	PRESTO	FORTE
I/O voltage	3–5 V native; 1.2–5.5 V with adapters	1.8–5.5 V built-in
Target supply	Fixed 5 V from USB (4.4–5.25 V); 3.3 V with HPR3V3; external	Variable 1.2–5.5 V
Voltage monitor	4-step (none / low / ~5 V / overvoltage)	0–5.5 V, 10 mV resolution
VDD discharge	Uncontrolled, 1 kΩ resistor	Controlled, 27 Ω fast discharge

Programming Interface

PRESTO uses an 8-pin ICSP connector (ICSPCAB8) exposing VPP, VCC, GND, and 4 data lines (2 bidirectional, 1 in, 1 out). This covers the vast majority of synchronous MCU programming protocols in common use.

FORTE upgrades to a 16-pin connector (ICSPCAB16) backward-compatible with PRESTO's 8-pin cable on the top row. The additional 8 pins expose 7 independent I/O lines with individually configurable pull-up/pull-down resistors — critical for devices that require non-standard handshake sequences or multiple chip-select signals during programming. The signals are interleaved with ground conductors on the 16-wire cable, enabling longer cable runs without signal integrity issues.

More importantly, FORTE's embedded processor supports asynchronous algorithms — UART-like protocols, UNI/O, 1-Wire, and other self-timed schemes — in addition to the synchronous JTAG and SPI/ISP modes PRESTO handles. This makes FORTE the correct choice for Dallas/Maxim 1-Wire devices, certain Cypress PSoC families, and any device whose programming spec doesn't tie to a clock signal.

PARAMETER	PRESTO	FORTE
Connector	8-pin ICSPCAB8	16-pin ICSPCAB16 (+ 8-pin compatible)
Data I/O	4 lines (2 I/O, 1 In, 1 Out)	7 I/O, configurable pull-up/down
Algorithms	Synchronous only	Synchronous + Asynchronous
JTAG support	Yes, via JTAG SVF Player	Yes, via JTAG SVF Player
1-Wire	Not supported	Supported (async)
Supply current limit	None	Fixed (current source)
OCP reaction	Software, depends on host PC	Hardware, independent of PC
ESD protection	Basic CMOS built-in	Extended TVS diodes

Supported Devices

Both programmers target a wide, overlapping range of devices and receive free software updates from ASIX. PRESTO covers the mainstream MCU families most workbenches use. FORTE supports everything PRESTO does, then extends further into 32-bit ARM, additional AVR variants, and several device families PRESTO can't reach at all.

PARAMETER	PRESTO	FORTE
32-bit ARM MCUs	Not supported	ATSAM3N4A, ATSAMD20E18A, AT91SAM7SE512, LPC11E14, LPC810, STM32F427IG, …
PIC / dsPIC/PIC24 / PIC32	All Flash + most popular OTP/JW parts	All Flash and EEPROM parts
Atmel/Microchip AVR	SPI low-voltage download + TPI — ATtiny12, AT90S8535, ATmega128, ATtiny10	AVR + ATxmega + AVR32 + 8051 arch. — ATtiny12, ATmega128, ATxmega32D4, AT32UC3A1256, AT89S51, …
8051-architecture MCUs	Supported — e.g. AT89S51	Supported — e.g. AT89S51
TI MSP430 / CC430	Supported — fuse blow & bootstrap loader NOT supported	Supported — incl. Security Fuse blowing & Bootstrap loader programming
Chipcon/TI CCxxxx	Supported	Supported
Cypress/Infineon PSoC	CY8C21xx, CY8C24xx, CY8C27xx	CY8C21xx, CY8C24xx, CY8C27xx
Dallas/Maxim 1-Wire	Not supported	DS24xx, 25xx, 28xx memories
Silicon Labs EFM8 / C8051	Not supported	EFM8BB22F16, EFM8SB10F8, C8051F326, C8051F968, …
ST STM8	Not supported	STM8S, STM8L, STM8A — e.g. STM8S207R8, STM8L152C4
Renesas RL78	Not supported	R5F10xx
JTAG components (SVF/XSVF)	CPLDs — Xilinx, Altera, Lattice; FPGA PROMs — XC18Vxx/XCFxxS; Atmel ATmega	Same families as PRESTO
Serial EEPROM (I2C/Microwire/SPI)	24LCxx, 93LCxx, 25Cxx	24LCxx, 93LCxx, 25Cxx
SPI Flash EPROM	Not supported	M25Pxx, M45PExx
UNI/O EEPROM	Not supported	11AAxxx, 11LCxxx

Software

Both programmers are controlled by the same UP application (with MultiUP for batch production use). The software is feature-complete for both: project management, command-line and Windows messaging control (useful for CI/CD-style programming automation), user-defined keyboard shortcuts, and flexible serial number generation strategies.

PRESTO also ships with the PRESTO DLL library for direct integration into third-party Windows applications — handy if you're writing a custom production test harness. FORTE uses the same UP/JTAG Player stack but doesn't have a separate DLL documented (it's controlled via UP's command-line and message interfaces).

Both work on Windows XP through 11, 32- and 64-bit. All device support and algorithm updates are free, distributed from the ASIX website.

Conclusion

Both programmers are well-built, field-proven tools that ship with free lifetime device updates. The question is whether your project needs what FORTE adds over PRESTO's core feature set.

Choose PRESTO when…

Your targets are mainstream and cost-effectiveness matters

• Programming Microchip PIC, AVR, TI MSP430, EEPROM, or standard Flash parts

• Your supply rail is 3.3 V or 5 V (or you already own HPR adapters)

• You need synchronous ISP/ICSP/JTAG and nothing more exotic

• Individual device or low-to-medium volume production

• You want a cost-effective entry into the ASIX ecosystem

• You need the DLL for custom host-application integration

 PRESTO Programmer with ISP2ZIF Socket

Choose FORTE when…

Speed, low voltage, or async protocols are non-negotiable

• Targets run at 1.8 V or 2.5 V and you don't want adapter hassle

• Programming 1-Wire, PSoC, STM8, or other async-algorithm devices

• Production throughput matters — you want to hit device max speed

• You're doing in-system programming across PCBs with longer cable runs

• You need hardware-level OCP independent of the host PC state

• Future - proofing: virtually any serially programmable device can be supported

If you already know you need sub-3 V support, asynchronous algorithms, or maximum throughput for production — the FORTE is the right call. If your work is squarely in the Microchip/AVR/TI/EEPROM mainstream and 3.3–5 V, PRESTO does everything you need. Both tools share drivers, software, and accessories — so upgrading later is painless.